Agilent Technologies 5500 Scanning Probe Microscope User’s Guide Agilent Technologies
Notices © Agilent Technologies, Inc. 2008 Manual Part Number No part of this manual may be reproduced in any form or by any means (including electronic storage and retrieval or translation into a foreign language) without prior agreement and written consent from Agilent Technologies, Inc. as governed by United States and international copyright laws. N9410-90001 Edition Rev B, September 2008 Printed in USA Agilent Technologies, Inc.
Read This First Read This First Warranty Agilent warrants Agilent hardware, accessories and supplies against defects in material and workmanship for a period of one year from date of shipment. If Agilent receives notice of such defects during the warranty period, Agilent will, at its option, either repair or replace products which prove to be defective. Replacement products may be either new or like-new.
Read This First Specifications Environmental Conditions Temperature (Operating): 5 to 40 °C Temperature (Non-operating): -40 to 70 °C Relative Humidity (Operating): 15 to 95 % non-condensing Altitude: 2000 m Power Requirements 100/120/220/240 VAC, 50/60 Hz Mains supply voltage fluctuations are not to exceed 10 % of the nominal supply voltage. NOTE These specifications apply to the Agilent 5500 system, and do not guarantee the function of an experiment (including the cantilever) in these conditions.
Read This First logotype (shown below). DO NOT stare directly into the laser beam. To ensure safe operation, the scanner must be operated and maintained in accordance with the instructions included with the laser. The laser must only be powered by a controller that includes an on/off switch, such as the Agilent SPM Controller. DO NOT attempt to make any adjustments to the laser, the laser’s electronics, or optics.
Read This First Piezo Scanner Precautions Piezo scanners are, by nature, very FRAGILE pieces of equipment. The piezo material that does the scanning is a ceramic and is consequently quite easily broken. Dropping a piezo scanner will result in damage to the scanner that can only be repaired by completely replacing the scanner piezo core. This can be an expensive and time-consuming process and so it is advised that the utmost care is used when handling the scanners. Agilent Technologies, Inc.
Read This First Technologies, Inc. Furthermore, Agilent Technologies, Inc. assumes no responsibility or liability for any misinformation, errors, or general inaccuracies that may appear in this manual.
Read This First Declaration of Conformity DECLARATION OF CONFORMITY According to ISO/IEC Guide 22 and CEN/CENELEC EN 45014 Manufacturer’s Name: Manufacturer’s Address: Supplier’s Address: Agilent Technologies, Incorporated 5301 Stevens Creek Boulevard Santa Clara, CA 95051 USA Declares under sole responsibility that the product as originally delivered Product Name: Model Number: Product Options: PicoPlus – Atomic Force Microscope Series 5500 This declaration covers all options of the above products c
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Contents Table of Contents Read This First Specifications 4 Laser Safety Information Power Supply 4 5 Piezo Scanner Precautions 6 General Care Requirements 6 Disclaimers 6 Declaration of Conformity Contact Information 8 9 1 Introduction to the Agilent 5500 Overview of Agilent SPM System SPM Basics 17 18 SPM Techniques 20 Scanning Tunneling Microscopy (STM) 20 Atomic Force Microscopy (AFM) 21 Contact Mode AFM 23 Intermittent Contact AFM 24 Acoustic AC (AAC) AFM 25 Magnetic AC (MAC) Mode 26
Contents Two-Piece Nose Assemblies Scanner 38 Detector 40 Sample Plates Video System 41 43 Head Electronics Box (HEB) AFM Controller 44 45 Vibration Isolation Chamber Software 36 46 47 System Options 48 MAC Mode 48 MAC III Mode 49 Liquid Cell 49 Temperature Control 50 Thermal K 50 Environmental Chamber 50 Glove Box 50 Electrochemistry 51 PicoTREC 51 PicoLITH 52 3 Setting Up the Agilent 5500 SPM Component and Facility Dimensions 53 Facility Requirements 55 Utilities 56 Noise and Facility Spe
Contents Removing the Body of the Two-Piece Nose Assembly 68 Inserting a Probe in the Two-Piece Nose Assembly 69 Inserting the Scanner and Connecting Cables 70 Aligning the Laser 72 Inserting and Aligning the Detector Mounting the Sample 79 83 Using the Video System 86 Care and Handling of the Probes and Scanner Probes 90 Nose Assembly 90 Two-Piece Nose Cone Cleaning 90 Scanner 90 90 5 Contact Mode Imaging Setting Up for Contact Mode Imaging Constant Force Mode 93 Constant Height Mode 100 Fine-Tunin
Contents Electrostatic Force Microscopy (EFM) Kelvin Force Microscopy (KFM) 130 134 8 Scanner Maintenance and Calibration Care and Handling of the Probes and Scanner Probes 138 Nose Assembly 138 Two-Piece Nose Cone Cleaning 139 Scanner 139 138 Scanner Characteristics 139 Non-Linearity 140 Sensitivity 140 Hysteresis 140 Other Characteristics 141 Bow 141 Cross Coupling 141 Aging 142 Creep 142 Calibrating the Multi-Purpose Scanner X Calibration 144 X Non-Linearity 145 X Hysteresis 146 X Sensitivity 147 Y
Contents 10 MAC Mode List of MAC Mode Components Connections 162 163 Hardware and Sample Setup 164 11 MAC III Mode Initial Setup 167 List of MAC III Components Connections 168 Hardware and Sample Setup 167 171 MAC III Software Controls 171 Simplified Software Control Options Contact Mode 172 AC AFM 172 STM 174 LFM 174 DLFM 174 FMM 175 EFM 177 KFM 180 Advanced Software Control Options Lock-In Tabs 183 Outputs Tab 185 Other Tab 188 171 182 12 Liquid Cell Liquid Cell with Standard Sample Plate Liqui
Contents Imaging 207 Tips for Temperature Controlled Imaging 208 14 Environmental Control Environmental Chamber Glove Box 209 212 15 Electrochemistry Equipment 216 Liquid Cell 216 Electrodes 216 Working Electrode and Pogo Electrode 216 Reference Electrode 217 Counter Electrode 217 Cleaning 218 Liquid Cell Cleaning 218 Non-Critical Applications 218 Critical Applications 218 Electrode Cleaning 219 Sample Plate Cleaning 219 Substrate Cleaning 219 Assembling and Loading the Liquid Cell Troubleshooting 2
Agilent 5500 SPM User’s Guide 1 Introduction to the Agilent 5500 Overview of Agilent SPM System 17 SPM Basics 18 SPM Techniques 20 Scanning Tunneling Microscopy (STM) 20 Atomic Force Microscopy (AFM) 21 Intermittent Contact AFM 24 Acoustic AC (AAC) AFM 25 Magnetic AC (MAC) Mode 26 Top MAC Mode 27 Current Sensing Mode (CSAFM) 27 Force Modulation Microscopy (FMM) 28 Lateral Force Microscopy (LFM) 29 Dynamic Lateral Force Microscopy (DLFM) 29 Magnetic Force Microscopy (MFM) 29 Electrostatic Force Microscopy (
Introduction to the Agilent 5500 1 Overview of Agilent SPM System The main component of the Agilent 5500 SPM system is the microscope (Figure 1), which includes the X/Y motion controls, scanner, high-resolution probe/tip, and detector. The control system for the microscope includes, at minimum, a high-speed computer, AFM controller and Head Electronics Box.
Introduction to the Agilent 5500 1 SPM Basics Scanning Probe Microscopy (SPM) is a large and growing collection of techniques for investigating the properties of a sample, at or near the sample surface. The SPM instrument has a sharp probe (with radius of curvature typically in the nanometers or tens of nanometers) that is in near-contact, intermittent contact, or perpetual contact with the sample surface.
Introduction to the Agilent 5500 1 collection of data points is then synthesized into the “SPM image,” a 3-dimensional map of the surface characteristic being examined. The most common SPM images are topography images, in which the third dimension, Z, for any given X/Y coordinates, is the relative height of the sample surface. This interpretation implies that the sharp probe does not deform the sample surface—the harder the sample surface, the more accurate is this interpretation.
Introduction to the Agilent 5500 1 SPM Techniques Scanning Tunneling Microscopy (STM) The earliest, widely-adopted SPM technique was Scanning Tunneling Microscopy (STM). In STM, a bias voltage is applied between a sharp, conducting tip and the sample. When the tip approaches the sample, electrons “tunnel” through the narrow gap, either from the sample to the tip or vice versa, depending on the bias voltage. Changes of only 0.
1 Introduction to the Agilent 5500 topography. Because the feedback response requires time, constant current mode is typically slower than constant height mode. However, greater variations in height can be accommodated. Figure 4 Constant Height mode STM (above) is faster but is limited to smooth surfaces; Constant Current mode (below) is capable of mapping larger variation in Z For electron tunneling to occur, both the sample and tip must be conductive or semi-conductive.
Introduction to the Agilent 5500 1 detector. As the cantilever bends, the position of the laser spot changes. The resulting signal from the detector is the Deflection, in volts. The difference between the Deflection value and the user-specified Set Point is called the “error signal.” Figure 5 Basic AFM principles Figure 6 shows the force interaction as the tip approaches the sample. At the right side of the curve the tip and sample are separated by large distance.
1 Introduction to the Agilent 5500 described below, can be generally described by their function within these three domains. Figure 6 Zones of interaction as the tip approaches the sample The tip-sample interaction is complicated by additional forces, including strong capillary and adhesive forces that attract the tip and sample. The capillary force arises when water, often present when imaging in the ambient environment, wicks around the tip, holding the tip in contact with the surface.
1 Introduction to the Agilent 5500 tip makes gentle contact with the sample, exerting from ~0.1-1000 nN force on the sample. AFM can be conducted in either constant height or constant force modes. In constant height mode, the height of the scanner is fixed as it scans. For small cantilever deflections (<500 nm) on hard surfaces, the error signal (in volts) is used to generate an image that is sensitive to small changes in topography, though actual topographic information is not obtained.
1 Introduction to the Agilent 5500 components.The complex tip-sample forces cause changes in the amplitude, phase and resonance frequency of the oscillating cantilever. Thus, topography, amplitude and phase can be collected simultaneously. The phase and amplitude images may highlight physical properties that are not readily discernible in the topographic map. For example, fine morphological features are, in general, better distinguished in amplitude and phase images.
1 Introduction to the Agilent 5500 amplitude—this reduction is used as a feedback signal to maintain constant amplitude of the cantilever motion. (Figure 7). NOTE Acoustic AC Mode is an option for the 5500 SPM and requires the additional Mac Mode or MAC III controller. Figure 7 Acoustic AC mode (AAC) Magnetic AC (MAC) Mode In Magnetic AC (MAC) Mode AFM, the back side of the cantilever is coated with magnetic material. A solenoid applies an AC magnetic field which is used to oscillate the cantilever.
Introduction to the Agilent 5500 Figure 8 1 Magnetic AC mode (MAC mode) Top MAC Mode In standard MAC Mode the magnetic coil is located in the sample plate, below the sample. A variant of MAC Mode, known as Top MAC, places the drive coil above the cantilever. This enables MAC Mode to be used with or without a sample plate, for large samples, or for samples which tend to dissipate the magnetic field enough to affect the resolution of regular MAC Mode.
1 Introduction to the Agilent 5500 between the conducting cantilever and sample, a current is generated which is used to construct a conductivity image. CSAFM is compatible with measurements in air, under controlled environments, and measurements with temperature control. The technique is useful in molecular recognition studies and can be used to spatially resolve electronic and ionic processes across cell membranes.
Introduction to the Agilent 5500 1 Lateral Force Microscopy (LFM) Lateral Force Microscopy (LFM) is a derivative of Contact AFM with the scan direction perpendicular to the long axis of the cantilever. In LFM, the tip is constantly in contact with the sample surface. In addition to its vertical deflection, the cantilever also twists in the scan direction.
1 Introduction to the Agilent 5500 cantilever due to interatomic magnetic force that persists for greater tip-sample separation than the van der Waals force. A standard topography image can be collected for the same scanned area, using AAC in Intermittent Contact mode. The two images can then be displayed side-by-side to highlight any correlation between the magnetic structure and topography. NOTE MFM requires MAC Mode or MAC III.
Introduction to the Agilent 5500 1 provides a quantitative analysis of changes in the applied or intrinsic electrostatic field of the sample. As in EFM mode, KFM uses a conductive tip and either standard AAC or MAC Modes. NOTE KFM is an option for the 5500 SPM and requires the additional MAC III controller.
Agilent 5500 SPM User’s Guide 2 Agilent 5500 SPM Components Microscope 34 Probes 35 Nose Assembly 36 One-Piece Nose Assemblies 36 Two-Piece Nose Assemblies 36 Scanner 38 Detector 40 Sample Plates 41 Video System 43 Head Electronics Box (HEB) 44 AFM Controller 45 Vibration Isolation Chamber 46 Software 47 System Options 48 MAC Mode 48 MAC III Mode 49 Liquid Cell 49 Temperature Control 50 Thermal K 50 Environmental Chamber 50 Glove Box 50 Electrochemistry 51 PicoTREC 51 PicoLITH 52 Agilent Technologies 32
Agilent 5500 SPM Components 2 The major components for the Agilent 5500 SPM are shown in Figure 10.
Agilent 5500 SPM Components 2 Microscope The microscope (Figure 11) includes the hinged support stand, coarse z-axis motors, manual X/Y positioning micrometers, magnetic supports for the sample plates, and interconnections for all electronics. The support stand is hinged to allow easy access to the sample plate area.
Agilent 5500 SPM Components 2 Probes The SPM techniques described in Chapter 1, “Introduction to the Agilent 5500,” are accomplished using either a wire tip (for STM) or, for AFM imaging, a tip at the free end of a cantilever (a “probe”). STM tips are made by cutting or electrochemical etching Platinum-Iridium or tungsten wire. AFM cantilevers are fabricated from silicon or silicon nitride with an integrated sharp tip at the end.
Agilent 5500 SPM Components 2 Nose Assembly The nose assembly retains the cantilever and enables its motion. A spring clip on the nose assembly secures the probe in place. The nose assembly is held securely in the scanner by an O-ring. One-Piece Nose Assemblies The most widely used nose assemblies consist of a single unit which is installed in the scanner (Figure 12). One-piece nose assemblies are available for different modes and may include additional electronics and/or components.
Agilent 5500 SPM Components 2 damage to the scanner during installation of the nose assembly. Currently the two-piece nose assembly is only available for AC Mode/Contact Mode imaging. CAUTION The two-piece nose assembly cannot be used for imaging in liquid.
Agilent 5500 SPM Components 2 Scanner The Agilent 5500 is a tip-scanning system, in which the cantilever sits on a scanner and is moved in raster fashion across the stationary sample. The scanner includes one or more elements made from piezoceramic material. When an electric field is applied to the piezo elements, they elongate or contract. The motion of the tip in the Z axis, and raster scanning in the X and Y axes, are all achieved by applying high voltages to the scanner’s piezo element(s).
Agilent 5500 SPM Components 2 • The large multi-purpose scanner includes four piezo elements for X and Y and provides scans up to 90 microns square. There are also 2 piezo tubes for Z motion. It provides high resolution and speed for general use applications. • The large multi-purpose scanner is also available with closed-loop positioning, in which ultra-precise positioning sensors measure displacement in the Z axis only, or X/Y/Z axes.
Agilent 5500 SPM Components 2 Detector The photodiode detector receives the reflection of the laser spot off the back of the cantilever. The top and bottom halves of the detector monitor the cantilever deflection (the Deflection signal) for AFM imaging, while the two side halves report cantilever twisting (the Friction signal) for lateral force imaging. The detector mounts in the scanner, typically while the scanner is on the microscope.Two thumbwheels on the detector enable alignment in both directions.
Agilent 5500 SPM Components 2 Sample Plates The Agilent 5500 SPM is designed to allow scanning from above the sample. A variety of sample plates provide mounting options and micro-environments for imaging (Figure 16). The standard sample plate has a magnetic core that will securely hold samples mounted on magnetic backings. Other plates are available for measurement in liquid, temperature controlled imaging, for MAC and other applications.
Agilent 5500 SPM Components 2 The microscope stand is equipped with three magnetic posts from which a sample plate is mounted (Figure 17). Micrometers enable manual X/Y positioning with total travel of ±5 mm.
Agilent 5500 SPM Components 2 Video System The video system lets you locate regions of interest and align the laser on the probe tip. It includes a camera and optics on an adjustable stand (Figure 18) along with a separate illumination source (Figure 19). A USB cable connects the camera to the computer.
Agilent 5500 SPM Components 2 Head Electronics Box (HEB) The Head Electronics Box (HEB) (Figure 20) reads the signals from the detector and can display the Sum signal (sum of all four quadrants) and the Deflection or Friction signals. The HEB also provides an oscillating voltage for AC Mode imaging.
Agilent 5500 SPM Components 2 AFM Controller The AFM Controller (Figure 22) provides the high voltage to the piezoes and other control functions. Model N9605A is standard; Model N9610A provides optional closed-loop scanning control.
Agilent 5500 SPM Components 2 Vibration Isolation Chamber The isolation chamber (Figure 23) isolates the 5500 SPM from vibration, air turbulence and acoustic noise which would adversely affect imaging. It also, to an extent, helps control temperature variability. The enclosure is considered a “mandatory option,” as the improvements it provides for imaging are essential for all but the most stringently controlled environments.
Agilent 5500 SPM Components 2 Software The Agilent 5500 SPM includes PicoView, a powerful software package for controlling all aspects of alignment, calibration, imaging and more. Also included is CameraView software for displaying video output, and PicoImage software for image analysis and data manipulation. To accomplish the steps in the following chapters you will need some familiarity with PicoView. The software steps will be documented briefly in this manual.
Agilent 5500 SPM Components 2 System Options Many options are available for the Agilent 5500 SPM. As discussed above, probes, nose assemblies and sample plates are available for particular applications. Scanner options include large and small scan ranges, closed-loop scanning, and a dedicated STM scanner. Other options include: MAC Mode The MAC Mode options includes the hardware required for MAC mode, which greatly improves imaging in fluid.
Agilent 5500 SPM Components 2 MAC III Mode MAC III Mode provides the benefits of regular MAC mode, provides three lock-in amplifiers for flexibility, enables EFM and KFM imaging, and provides “Q control” for more precise control of cantilever oscillation. Liquid Cell The sample plate for liquid enables liquid imaging. A flow-through liquid cell is also available with connections for tubing. A schematic drawing of the liquid cell is shown below in Figure 25.
Agilent 5500 SPM Components 2 Temperature Control This option includes low and/or high temperature sample plates, a temperature controller and related hardware for maintaining sample temperature during imaging. Thermal K Thermal K provides a method for accurately determining the force constant of the cantilever for highly accurate force measurements. By measuring the thermal oscillation of the cantilever with no drive signal applied, the cantilever force constant can be determined.
Agilent 5500 SPM Components 2 environment, it is possible to perform experiments under very reactive conditions without damaging the system or the sample. Figure 27 Glove box Electrochemistry The electrochemical SPM option includes a low-noise potentiostat/galvanostat for in-situ EC-STM and EC-AFM. When combined with temperature control, it is possible to obtain valuable information about electrochemical processes that would otherwise be inaccessible.
Agilent 5500 SPM Components 2 dynamic properties of biological systems by imaging patterns of molecular binding and adhesion on surfaces. Figure 28 PicoTREC controller PicoLITH PicoLITH is an optional package for nanoscale positioning and manipulation, and nanolithography. The PicoLITH option includes its own documentation and is not covered in this manual.
Agilent 5500 SPM User’s Guide 3 Setting Up the Agilent 5500 SPM Component and Facility Dimensions 53 Facility Requirements 55 Utilities 56 Noise and Facility Specifications 56 Acoustic Noise 56 Temperature and Humidity Variation 57 Connecting the Components 58 Guidelines for Moving the System 58 The Agilent 5500 SPM is typically installed by trained Agilent technical staff. This chapter includes information on the facilities requirements and preparation needed prior to installation.
Setting Up the Agilent 5500 SPM 3 • MAC III Controller: 254 mm W x 127 mm H x 254 mm D (10 in W x 5 in H x 10 in D) • Vibration Isolation Chamber: 495 mm W × 940 mm H × 483 mm D (19.5 in W x 37 in H x 19 in D) The most common system configuration includes the 5500 SPM within a vibration isolation chamber, with the controls on a separate table from the rest of the components, as shown in Figure 29 (top and front views).
Setting Up the Agilent 5500 SPM 3 Facility Requirements Following these guidelines for preparing the Agilent 5500 SPM facility will ensure a smooth installation, will make using the system more convenient and will improve system performance for the life of the SPM: • Minimize the acoustic noise level from all possible sources, such as paging speakers, telephone ringer, air conditioner, especially during data acquisition.
Setting Up the Agilent 5500 SPM 3 Utilities The following table summarizes the utility requirements for the Agilent 5500 SPM.
Setting Up the Agilent 5500 SPM 3 acoustic noise should be less than 75 dBc (Criterion C). Use of the vibration isolation chamber will help considerably in meeting this goal. Figure 30 Vibration criterion curves and ISO guidelines Temperature and Humidity Variation Changes in temperature and humidity will affect both resolution and repeatability of imaging. Temperature variation should be limited to ±2 degrees Fahrenheit. Humidity variation should not exceed ±20 % RH.
Setting Up the Agilent 5500 SPM 3 Connecting the Components The cabling for the standard 5500 SPM is shown in Figure 31. Other cabling configurations are included in Appendix A. Figure 31 Cabling for basic 5500 SPM configuration CAUTION Always make sure that all cables are connected before turning on any of the components. Failure to do so can result in damage to equipment.
Agilent 5500 SPM User’s Guide 4 Preparing for Imaging Setting Up the Scanner Assembly 59 One-Piece Nose Assembly 60 Inserting the One-Piece Nose Assembly 60 Removing the One-Piece Nose Assembly 62 Inserting a Probe in the One-Piece Nose Assembly 64 Two-Piece Nose Assembly 67 Inserting the Body of the Two-Piece Nose Assembly 67 Removing the Body of the Two-Piece Nose Assembly 68 Inserting a Probe in the Two-Piece Nose Assembly 69 Inserting the Scanner and Connecting Cables 70 Aligning the Laser 72 Inserting
Preparing for Imaging 4 voltages to opposite piezo elements in the scanner so that one element elongates and the other contracts. CAUTION The thickness of the piezo elements determines how much they will expand or contract per applied unit voltage. They are necessarily thin to provide scanning resolution. If dropped, the scanner’s piezo elements WILL break. Cracked or broken piezoelectrodes will result in abnormal imaging.
Preparing for Imaging 4 scanner mounting fixture (Figure 32). Place the nose assembly in the socket on top of the scanner, aligning its contact pins if applicable. Applying even, steady, vertical pressure at the edges of the nose assembly, seat it into the socket, as shown in Figure 33. Figure 33 Applying even, vertical pressure at the edges to insert the nose assembly. CAUTION Push evenly and straight down when inserting the nose assembly.
Preparing for Imaging 4 Removing the One-Piece Nose Assembly A removal tool is included with your system to limit damaging, lateral forces on the scanner while removing the nose assembly. The following is the only acceptable procedure for removing the nose assembly: Figure 34 Nose assembly removal tool 1 Place the scanner in the scanner mounting fixture. 2 Carefully slide the removal tool onto the nose assembly, ensuring that the opening seats on both sides of the nose.
Preparing for Imaging 4 5 Once the nose assembly is clear of the scanner you can remove it from the tool. Figure 35 Using the nose assembly removal tool CAUTION Do not use the nose removal tool to insert a nose assembly. It is not designed for this purpose. CAUTION DO NOT use tweezers to remove the nose assembly (Figure 36).Tweezers can create a pivot point to lever the nose out of the scanner, placing large lateral forces on the piezo assembly.
Preparing for Imaging 4 Figure 36 Do not use tweezers to remove a nose assembly. Doing so can place damaging lateral forces on the scanner. Inserting a Probe in the One-Piece Nose Assembly Agilent nose assemblies are designed with a spring and guides to retain the probe in the proper position for imaging. A spring key (Figure 37) is included with the system to let you safely hold back the spring while inserting the probe. Figure 38 shows a properly positioned probe.
Preparing for Imaging 4 Figure 38 Probe properly situated on AFM nose assembly AFM probe tips are extremely delicate and can break when dropped even a short distance. The following instructions include several helpful tips that will simplify the process of inserting a probe in the nose assembly: 1 Mount the nose assembly in the scanner. 2 Place the scanner into the scanner mounting fixture. 3 Grasp the tweezers in the orientation shown in Figure 39.
Preparing for Imaging 4 Figure 39 Holding the tweezers as shown, remove a probe from the protective case 5 With your free hand, use the spring key to rock back the retainer spring (Figure 40). 6 Place the probe between the guides such that a little more than half of the probe extends over the lens (placement will vary depending on the type and shape of the probe). Figure 40 shows this process. The final probe position should be as shown in Figure 38 on page 65.
Preparing for Imaging CAUTION 4 The retainer spring can snap back with enough force to damage the probe, so be sure to release the spring slowly and gently. Two-Piece Nose Assembly The two-piece nose assembly was designed to simplify the process of inserting a probe through the use of an assembly fixture (Figure 41). The nose assembly consists of a body, which inserts into the scanner, and a flat, stainless steel disk which holds the cantilever.
Preparing for Imaging 4 page 60). Place the body in the socket on top of the scanner, aligning its contact pins. Applying even, steady, vertical pressure with your fingers to seat the body into its socket. CAUTION It is essential to push evenly and straight down when inserting the nose assembly. Small off-axis forces will create LARGE torques about the anchor point for the piezoes, where most breakage occurs.
Preparing for Imaging 4 Inserting a Probe in the Two-Piece Nose Assembly AFM probe tips are extremely delicate and can break when dropped. Follow these instructions to safely insert a probe in the nose assembly: 1 Place the nose assembly disk on the assembly fixture, as shown in Figure 43. Make sure that it aligns with the center disk and two small alignment pins.
Preparing for Imaging 4 Figure 44 Move the lever to open the nose assembly disk. 4 Place the probe under the copper-colored spring clip on the nose assembly disk. Use the alignment guides in the fixture to help locate the probe laterally. 5 A small alignment spot on the fixture (Figure 43 on page 69) indicates the proper location for the cantilever tip. Place the probe such that the tip is close as possible to this spot. 6 Move the lever to the left to close the nose assembly disk.
Preparing for Imaging 4 Figure 45 Placing scanner assembly into microscope 3 Finger-tighten the knob on the right side of the microscope to lock the scanner in position. 4 Attach the high voltage (red) and low voltage (blue) cables on either side of the scanner to the sockets on the microscope base. The cables are color coded to avoid confusion. If you are using a closed-loop scanner, connect its third cable to the C/L socket on the rear of the Head Electronics Box.
Preparing for Imaging 4 Aligning the Laser The next step is to ensure that the scanner’s laser spot is aligned to reflect off of the cantilever. Several methods can be used to do so. One method is to place a white card or piece of paper under the scanner to make the laser spot visible. By moving the laser you can then align it on the probe—when this happens the probe will block the laser spot, and the spot will no longer be visible on the paper.
Preparing for Imaging 4 cantilever tip (counterclockwise) or away from it. The left-to-right knob adjusts the lateral position. Figure 47 Use the scanner knobs to position the laser spot 3 Rotate the front-to-back knob clockwise to move the laser spot onto the cantilever chip (Diagram B in Figure 48). When the laser reaches the chip it will be blocked and will no longer be visible on the paper. You should only need to turn the knob a few rotations.
Preparing for Imaging 4 Figure 48 Steps to aligning laser on cantilever beam tip 4 Rotate the front-to-back knob counterclockwise until the spot just reappears on the paper. The spot is now at the edge of the chip (Diagram C in Figure 48). 5 Rotate the left-to-right knob to position the laser on the cantilever (Diagram D in Figure 48). As the laser passes over the cantilever it will disappear and reappear in rapid succession. You should now see the laser spot on the scanner’s frosted glass.
Preparing for Imaging 4 The process is similar for triangular-shaped cantilevers, with the exception that the laser will be obscured twice as it moves left to right (over the two beams). The process is shown in Figure 49. Figure 49 Steps to aligning the laser on triangular cantilevers A potential error during the alignment process is to turn either of the positioning controls too far in the wrong direction and to thereby lose the laser spot altogether.
Preparing for Imaging 4 back to the center of its travel in both directions. Doing so should make the laser spot reappear. Figure 50 Laser alignment control when far out of alignment In some cases, particularly with highly reflective samples, you can use the 5500 SPM’s video system to focus on the cantilever and align the laser spot (Figure 51). The laser spot will be visible in the video image until it crosses the cantilever, so you can use a similar procedure to the paper method above.
Preparing for Imaging 4 Figure 52 shows how the position of the laser on the cantilever affects the position of the laser. Due to the variation of cantilever types and vendors, the position of the cantilever needs to be optimized per tip.
Preparing for Imaging 4 Note that the IR sensor card should be used for coarse positioning of the laser if using the 980 nm IR scanners.
Preparing for Imaging 4 Inserting and Aligning the Detector As mentioned earlier, the photodiode detector records changes in the position of the laser spot as the cantilever passes over the sample surface. As shown in Figure 54, the detector senses the laser’s movement between its four quadrants, reporting the AFM (vertical deflection), LFM (lateral, or friction), and SUM signals.
Preparing for Imaging 4 microscope base. You can install the detector into the scanner before or after installing the scanner in the microscope base. Figure 55 Inserting the detector module into the scanner The Gain Switches on the detector determine whether the laser signal is amplified before going to the rest of the electronics. Up (away from the adjustment wheels) means no amplification, down means the signal is amplified. Each switch represents one of the four quadrants in the photodetector.
Preparing for Imaging 4 The Friction signal is the difference between the left and right halves divided by the Sum. NOTE These signals can also be seen on the Head Electronics Box where Meter A is the Sum signal reading and Meter B shows Deflection and Friction (LFM) depending on the state of the switch directly below the meter. Figure 56 Laser Alignment window in PicoView 2 Use the knobs on the detector to move the laser spot to the center of the four quadrants.
Preparing for Imaging 4 3 For Contact Mode, The dotted yellow line shows the recommended vertical alignment of the laser prior to approaching the sample.
Preparing for Imaging 4 Mounting the Sample The Agilent 5500 SPM accepts a wide variety of sample plates, including specialized plates for imaging in liquid, in controlled temperature, etc. To use a sample plate: 1 Mount the sample to the sample plate. In general, samples should be held in place securely enough to prevent drift or creep during measurement, but not so firmly as to induce stress in the sample. Several mounting methods are available.
Preparing for Imaging 4 Figure 58 Mounting a sample plate. 3 Place the second alignment tab over the alignment pin as in image B of Figure 58.
Preparing for Imaging 4 4 Let the magnets on the three posts gently engage the sample plate to hold it in place, as in image C of Figure 58. CAUTION The sample plate magnets are quite strong and, if allowed to, will snap the sample plate into position, which may perturb the sample. Holding the plate at the edges while engaging the magnets will control this movement.
Preparing for Imaging 4 Using the Video System The Agilent 5500 SPM includes a USB-based video system for viewing the tip and sample. The video system’s optics and optics in the scanner together provide optical magnification of 3.8X - 24.3X to the camera. The video system’s illuminator is a separate box (Figure 59) connected to the video system by a fiber light pipe. The light pipe can be separated from the illuminator and/or optics by loosening the knobs at either of its ends.
Preparing for Imaging 4 The z-position knob (Figure 60) lets you raise and lower the video system optics. Typically the optics are situated 3.5 inches above the scanner; this position is set by a stop ring on the pole. You may need to adjust this level to accommodate the Environmental Chamber or other optional hardware.
Preparing for Imaging 4 clockwise to move the field-of-view to the right, and counterclockwise to move left. Figure 61 Adjusting lateral position of the video system Twist the Zoom control (Figure 62) to the left to increase the zoom, or to the right to decrease zoom.
Preparing for Imaging 4 Choose Controls > CameraView to view the video output from the camera (Figure 63). Figure 63 CameraView video window showing tip and sample.
Preparing for Imaging 4 Care and Handling of the Probes and Scanner Probes Always store probes at room temperature in their protective cases. Handle probes gently with tweezers, following the procedures described earlier in this chapter. If a probe is dropped it may very well be damaged. You can check whether the cantilever is intact by viewing it through a magnifier. If you are using more than one type of probe, be sure to store them separately in well-marked cases to avoid confusion.
Preparing for Imaging 4 to excessive humidity, temperature changes or contact. Agilent recommends that scanners be stored in a desiccator. The scanner contains very brittle and fragile piezoelectric ceramics. Applying excessive lateral force while exchanging nose assemblies, or dropping the scanner even a short distance onto a hard surface, will damage the scanner. If the nose assembly housing becomes loose or can be wiggled when in place, contact Agilent support for assistance.
Agilent 5500 SPM User’s Guide 5 Contact Mode Imaging Setting Up for Contact Mode Imaging Constant Force Mode 93 Constant Height Mode 100 Fine-Tuning the Image 100 Setpoint 100 Gains 101 Scan Settings 101 93 In Contact Mode imaging, the AFM tip is brought into gentle contact with the sample and then scanned in raster fashion across the sample surface.
Contact Mode Imaging 5 Setting Up for Contact Mode Imaging Contact Mode imaging can be completed with any of the multi-purpose scanners, using most any AFM probe and nose assembly. Contact Mode tips, however, are designed specifically for this application, with lower resonance frequency, softer cantilevers.
Contact Mode Imaging 5 Figure 64 Tip in focus through video system b Lower the focal plane just slightly below the tip by turning the Z-position control toward you until the tip is slightly out of focus (Figure 65). Figure 65 Lower focal plane just below tip c Agilent 5500 SPM User’s Guide Using the Close switch on the HEB, raise the sample until the sample comes nearly into focus. The tip should now be just above the sample surface.
Contact Mode Imaging CAUTION 5 Raise the sample slowly and carefully to avoid collision with the sample. Hard contact between the tip and the sample can damage either or both. 11 Locate the area of interest on the sample by manually moving the X/Y stage control micrometers (Figure 66) while watching the video window. Figure 66 Stage control micrometers CAUTION If your sample has tall features or steps, you may need to raise the scanner slightly to avoid contacting features as you move the stage.
Contact Mode Imaging 5 Figure 67 Servo window showing Setpoint voltage and Gains NOTE If the Servo window is not already open, choose Controls >Imaging to open it. The Scan and Motor and Real Time Images windows will also open at the same time. 13 Click the Approach button in PicoView’s toolbar . The system will raise the sample until the deflection reaches the Setpoint value.
Contact Mode Imaging 5 changes in tip deflection in order to maintain constant force. 10 % is a good starting value; more information on optimizing the gains is in“Gains" on page 101. 15 In the Scan and Motor window, select the Scan tab (Figure 68). Figure 68 Scan and Motor window: Scan tab 16 Enter a scan Speed, stated in Lines/Second (ln/s). A typical starting value is 1-2 ln/s. 17 Select a resolution from the X list.
Contact Mode Imaging 5 buffer frame, then select the Input Signal from the list (Figure 69). The list will vary depending on the imaging mode. Figure 69 Selecting the Input signals in the Realtime Images window 20 In the Scan and Motor window, click the Down blue arrow to initiate a scan starting at the top of the grid. Click the Up blue arrow to initiate the scan from the bottom up (Figure 70). The image maps will begin to be rendered in the Realtime Images window.
Contact Mode Imaging 5 Figure 70 Scan and Motor window after scan has been initiated As the tip moves across the first scan line, the system will adjust the voltage on the z-piezo actuator to maintain constant force (as specified by the Setpoint value). NOTE The important parameter is the difference between the Deflection setting (shown on the HEB) before beginning the approach and the initial Setpoint value. A Setpoint of +1 V could be too low if the initial Deflection was -0.
Contact Mode Imaging 5 two components. Comparing the friction and topography images helps to differentiate the impact of topography versus friction. At the end of each scan line the system will “retrace” the scan line until it once again reaches the beginning. The scanner will then advance one line width and another line will be scanned.
Contact Mode Imaging 5 tip. Higher force can place undue wear on the tip and, in the extreme, can damage the tip or sample. The optimal Setpoint value, which will vary per sample and per probe, places enough force on the tip to accurately trace the topography without placing unnecessary force on the tip. A good method for setting the Setpoint is as follows: 1 With your cursor still in the Setpoint box, press the Down arrow on your keyboard to make the Setpoint more negative.
Contact Mode Imaging 5 speed will be 2-5 lines/second for smooth surfaces. For rougher surfaces a lower scan speed may be needed. A typical resolution of 256 pixels/line provides good resolution and speed. Increasing the resolution will improve image quality but will require longer imaging times. One good option is to scan a large region at low resolution and high speed, and then to zoom in on a region of interest for a high resolution scan at lower speed.
Agilent 5500 SPM User’s Guide 6 AC Modes Acoustic AC Mode (AAC) 104 AAC Mode 104 Constant Height Mode 109 Magnetic AC (MAC) Mode 110 Standard MAC Mode 111 Top MAC Mode 112 Q Control 112 In AC Mode, introduced in “Intermittent Contact AFM" on page 24, a sinusoidal voltage is applied to a piezo element or magnetic coil in the nose assembly or sample plate.
AC Modes 6 Acoustic AC Mode (AAC) In Acoustic AC (AAC) Mode AFM, a piezo-electric transducer in the nose assembly drives the cantilever oscillation. Note that the nose assembly (Figure 71) includes two contact pins through which the drive signal is routed to the transducer. AAC Mode probe cantilevers have resonance frequencies typically in the 100-300 kHz range. Any sample plate can be used.
AC Modes 6 5 Choose Controls > AC Mode to open the ACAFM Controls window (Figure 72). Figure 72 ACAFM Controls window 6 Set the Drive Mechanism to AAC. 7 Set the Drive% to 10 %. This is the amplitude of the AC drive signal, stated as a percentage (0-100 %) of the maximum available 10 V. 8 In the Servo window set the Setpoint to 0 (the Setpoint must be zero in order to perform an Auto Tune with the HEB as the AC source).
AC Modes 6 Figure 73 AC Mode Tune window Figure 74 AC Tune window with resonance peak at ~154.4 kHz 10 The next step is to tune the oscillation signal to match the frequency of the particular cantilever. You will use the controls in the AC Mode Tune window to sweep through a range of frequencies. The resultant plot should show one strong, sharp resonance peak.
AC Modes 6 storage box should indicate the range in which the primary resonance frequency will be found. 11 In the upper Auto Tune area of the AC Mode Tune window, enter the Start and End frequencies (in kHz) for the tuning sweep. For a new or unknown cantilever, use the stated minimum and maximum frequencies given on the storage box. If you happen to know the resonance frequency more exactly, you can use a smaller range to speed the tuning process.
AC Modes 6 Next, bring the tip into contact with the sample. In AAC mode, “contact” occurs when the cantilever oscillation is dampened to a specified percentage of the total oscillation. 18 In the Scan and Motor window, click the Motor tab (Figure 75). Figure 75 Set the Stop At value in the Scan and Motor window 19 Set the Stop At% to specify the percentage of total oscillation that represents “contact.
AC Modes 6 25 In the Realtime Images window, make sure that Topography and Deflection are displayed. 26 In the Scan and Motor window, click the Down blue arrow to initiate a scan starting at the top of the grid. Click the Up blue arrow to initiate the scan from the bottom up. The image maps will begin to be rendered in the Realtime images window.
AC Modes 6 response to amplitude changes. This lack of feedback reduces signal noise, enabling high resolution imaging of very flat samples. The change in amplitude as the tip scans across the sample is mapped as Amplitude and displayed in volts in the Image buffer. Magnetic AC (MAC) Mode In Magnetic AC (MAC) Mode AFM, a cantilever coated in magnetic material is driven by a coil-generated oscillating magnetic field.
AC Modes 6 MAC III offers additional lock-in amplifiers for other more complex modes as well). Specially coated MAC cantilevers are also required. Standard MAC Mode In standard MAC Mode, the coil is located in the sample plate (Figure 76). A Contact Mode or AC Mode nose assembly can be used.
AC Modes 6 2 In the ACAFM Controls dialog box, choose MAC as the Drive Mechanism. Top MAC Mode In Top MAC Mode AFM, the driver coil is located in the nose assembly (Figure 78). This configuration provides better tip response when imaging thick samples which can lessen the magnetic field oscillating the tip. Any sample plate can be used for Top MAC imaging.
AC Modes 6 well-defined resonant peak in MAC Mode makes the method particularly effective. Q Control uses a feedback loop to alter the sharpness of the resonance peak. It is only available with the MAC III controller, and it can be used with either AC Mode or MAC Mode. To use Q Control, select the On check box in the ACAFM Controls window. Set the Drive%, which is the amplitude of the Q Control feedback signal, stated as a percentage of maximum.
Agilent 5500 SPM User’s Guide 7 Additional Imaging Modes Scanning Tunneling Microscopy (STM) 114 Current Sensing AFM (CSAFM) 119 Lateral Force Microscopy (LFM) 123 Dynamic Lateral Force Microscopy (DLFM) 125 Force Modulation Microscopy (FMM) 127 Electrostatic Force Microscopy (EFM) 130 Kelvin Force Microscopy (KFM) 134 One of the primary advantages of the Agilent 5500 SPM is that it allows you to perform many different imaging modes with the same basic hardware.
Additional Imaging Modes 7 available with three different preamplifiers for varying sensitivity (Table 2). Figure 80 STM nose assembly Table 2 STM nose assembly and scanner sensitivities Color Red Blue Green Sensitivity 10 nA/v 1 nA/V 0.1 nA/V Bandwidth 20 kHz 6.3 kHz 2 kHz Test Resistor 10 G 1 G 100 M A dedicated STM scanner (Figure 81) provides lower current operation and higher resolution.
Additional Imaging Modes 7 located beneath the tip, can be field-replaced to adjust the sensitivity if necessary. Figure 81 STM scanner The procedure for STM imaging is as follows: 1 If you are using the multi-purpose scanner, insert the nose assembly into the scanner (see Chapter 4 for details). 2 Insert a tip into the nose assembly or scanner. Grasp the tip with a tweezers, then insert it into the hollow tube until it protrudes approximately 2 mm (Figure 82).
Additional Imaging Modes 7 5 Attach an electrode from the sample plate to the sample. Lift the spring-loaded electrode clip on the sample plate and insert the electrode under it (Figure 83). Connect the electrode to the sample, ensuring good contact. Figure 83 Sample on plate with electrode attached 6 Place the sample plate on the microscope. 7 Plug the 3-pin EC connector of the EC/MAC cable into the 3-pin socket on the sample plate.
Additional Imaging Modes 7 Figure 84 Servo window settings for STM imaging 10 Enter the Setpoint current, in nanoamps, that the system will try to hold constant during scanning. A typical setting is 1-2 nA. 11 Enter the I and P gains for the z-servo, which will dictate how quickly the system will adjust to changes in tunneling current. Typical values are 1-2 % for both gains. 12 In the Realtime Images window choose to display images for Current and Topography.
Additional Imaging Modes 7 Current Sensing AFM (CSAFM) In Current Sensing AFM (CSAFM) an ultra-sharp AFM cantilever, coated with conducting film, probes the conductivity and topography of the sample surface. CSAFM requires a special 9 ° nose cone containing a pre-amp. A bias voltage is applied to the sample while the cantilever is kept at virtual ground (Figure 85). As in Contact Mode, the tip force is held constant throughout the scan. The current is used to construct the Conductivity image.
Additional Imaging Modes 7 1 nA/V (blue) or 0.1 nA/V (green). See Table 2 on page 115 for more details. Figure 86 CSAFM nose assembly and scanner Platinum-coated, conductive tips are required for CSAFM imaging. Because an electrode must be attached to the sample, a sample plate is also required. To image in CSAFM Mode: 1 Begin with the steps you learned in Chapter 4: a Insert the nose assembly into the scanner. b Load a probe into the nose assembly.
Additional Imaging Modes NOTE 7 The sample plate cable can transfer low levels of vibration to the sample. During very high resolution imaging this can affect resolution. We recommend first plugging the sample plate cable to the 3-wire umbilical included with the sample plate. The umbilical should then be plugged in to the microscope base. The umbilical’s individual wires tend to reduce the transfer of vibration. 6 In PicoView, choose Mode > CSAFM. 7 In the Servo window enter the Bias Voltage.
Additional Imaging Modes 7 14 Watching the video system, bring the tip and sample very close to contact: a Adjust the focus and location of the video such that the tip is in sharp focus. b Lower the focal plane just slightly below the tip by turning the Focus control toward you until the tip is slightly out of focus. c CAUTION Now, using the Close switch on the HEB, raise the sample until the sample comes nearly into focus. The tip should now be just above the sample surface.
Additional Imaging Modes 7 Lateral Force Microscopy (LFM) Lateral Force Microscopy is a derivative of Contact Mode. During a typical scan, the cantilever twists in the scan direction as well as deflecting in the vertical axis. The detector senses change in the cantilever‘s twisting motion and outputs it as the lateral deflection (Friction) signal. Changes in lateral force on the tip can be caused either by changes in frictional properties across the sample or by variations in topography.
Additional Imaging Modes 7 NOTE It is important in LFM that the LFM signal on the Head Electronics Box be carefully set as close to zero as possible.
Additional Imaging Modes 7 Dynamic Lateral Force Microscopy (DLFM) In Dynamic Lateral Force Microscopy (DLFM), a lead zirconate titanate (PZT) ceramic element in the nose cone oscillates the tip parallel to the sample surface, in the direction of the scan (as opposed to perpendicular oscillation as in AC Mode). Cantilever deflection is mapped to give topography, as in contact mode. Changes in the amplitude and phase of the lateral oscillation are imaged.
Additional Imaging Modes 7 6 Bring the tip close to the sample: a Press the Close switch on the HEB to raise the sample until the tip is close to, but not touching, the sample. b Focus the cantilever in the video window. c Turn the video system focus knob toward you such that the tip goes just out of focus. d Press the Close switch to raise the sample until both the tip and sample are in focus (i.e., they are nearly touching).
Additional Imaging Modes 7 12 In the Scan and Motor window’s Scan tab, enter: a Scan Speed of 1-2 ln/s. b Resolution of 256. c Scan Size (in microns). d X Offset and/or Y Offset values to set the center of the scan. 13 In the Realtime Images window, choose to display Topography, CSAFM/BNC Aux (Amplitude) and PicoPlus Aux (Phase). If using a MAC III controller select Aux 1 and Aux 2. 14 In the Scan and Motor window, click the Up blue arrow to initiate a scan starting at the bottom of the grid.
Additional Imaging Modes 7 For the MAC III controller these connections are made in software. To image in Force Modulation Mode: 1 First follow the steps from Chapter 4 a Insert the nose assembly into the scanner. b Insert a probe into the nose assembly. c Place the scanner in the microscope base. d Align the laser on the cantilever. e Insert and align the detector. f Prepare the sample and place it on the sample plate.
Additional Imaging Modes 7 9 Now set up the additional AC oscillation: a Choose Controls > AC Mode to open the ACAFM Controls window. b Set the Drive Mechanism to AAC. c Set the Drive% to 10 %. d Set the Frequency to 20-50 kHz. 10 In the Servo window set the I Gain and P Gain to 5 %. 11 In the Scan and Motor window’s Scan tab, enter: a scan Speed of 1-2 ln/s. b Resolution of 256. c scan Size (in microns). d X Offset and/or Y Offset values to set the center of the scan.
Additional Imaging Modes 7 Electrostatic Force Microscopy (EFM) Electrostatic Force Microscopy (EFM) is a qualitative method for examining changes in the intrinsic or applied electrostatic field of a sample surface. EFM is a derivative of AAC Mode, using a conductive tip. A bias voltage is applied to the sample, allowing local static charge domains and charge carrier density to be measured.
Additional Imaging Modes 7 6 Choose Controls > Advanced > AC Mode. The EFM Controls window will open (Figure 88). Figure 88 EFM Controls window 7 In the Main tab, set up the Lock-in 1 AC signal which drives the cantilever oscillation: a Set the Drive% to 10 %. b Set the Gain to x1 (the amplitude times 1). 8 Choose Controls > AC Mode Tune to open the AC Mode Tune window.
Additional Imaging Modes 7 10 Bring the tip close to contact with the sample: a Press the Close switch on the HEB to raise the sample until the tip is close to, but not touching, the sample. b Focus the cantilever in the video window. c Turn the video system focus knob toward you such that the tip goes just out of focus (the focal plane is just below the tip now). d Press the Close switch to raise the sample until both the tip and sample are in focus (i.e., they are nearly touching).
Additional Imaging Modes 7 amplitude exceeding 10 V, beyond which the signal will be clipped. The default value is x1 (the amplitude times 1). e Select the EFM Tune check box. f In the AC Mode Tune window, set the Start and End frequencies for the EFM tune sweep. Use a wide range centered on the Lock-in 2 frequency. g Click the Manual Tune button. The system will sweep Lock-in 2 through the range of frequencies, displaying any peak oscillation amplitude within the range.
Additional Imaging Modes 7 Kelvin Force Microscopy (KFM) Kelvin Force Microscopy (KFM) is similar to EFM. An additional feedback loop applies a DC bias to the tip to counteract deflection due to the surface electrostatic force. The output from this feedback loop provides a quantitative analysis of changes in the applied or intrinsic electrostatic field of the sample.
Additional Imaging Modes 7 4 Choose Controls > Spectroscopy to open the Spectroscopy window (Figure 90). Figure 90 Use the Spectroscopy window to optimize the Setpoint value 5 Select Amplitude vs Distance at the top of the Main tab. 6 On the Advanced tab set the Aux 1 Input to SP. 7 On the Lock-in 2 tab verify that the From Servo box is not checked.
Additional Imaging Modes 7 For more on advanced options for KFM Mode see Chapter 11.
Agilent 5500 SPM User’s Guide 8 Scanner Maintenance and Calibration Care and Handling of the Probes and Scanner 138 Probes 138 Nose Assembly 138 Two-Piece Nose Cone Cleaning 139 Scanner 139 Scanner Characteristics 139 Non-Linearity 140 Sensitivity 140 Other Characteristics 141 Bow 141 Cross Coupling 141 Aging 142 Creep 142 Calibrating the Multi-Purpose Scanner 143 X Calibration 144 X Non-Linearity 145 X Hysteresis 146 X Sensitivity 147 Y Calibration 147 Y Non-Linearity 148 Y Hysteresis 149 Y Sensitivity 15
Scanner Maintenance and Calibration 8 Care and Handling of the Probes and Scanner Probes Always store probes at room temperature in their protective cases. Handle gently with tweezers, following the only the described procedures. If a probe is dropped it may very well be damaged. You can check whether the cantilever is intact by viewing it through a loupe or other magnifying device. If you are using more than one type of probe, be sure to store them separately in well-marked cases to avoid confusion.
Scanner Maintenance and Calibration 8 nose assembly will likely need to be replaced. Use careful handling to avoid damaging the window. Only remove the nose assembly from the scanner using the Nose Assembly Removal Tool, with the scanner placed upright in its fixture. Do NOT use the Removal Tool to install the nose assembly in the scanner. Two-Piece Nose Cone Cleaning The two-piece nose cone is not to be used in liquid because it does not have a glass window to prevent liquid from getting to the scanner.
Scanner Maintenance and Calibration 8 explained below. Though they are explained separately for simplicity, they may not be independent of each other. All Agilent scanners are calibrated before shipment and installation. A unique calibration file is provided with each system, as is a “generic” calibration file, which is not scanner-specific. Non-Linearity Figure 91 shows a calibration target consisting of square features of known size and equal spacing. The image was made with an uncalibrated scanner.
Scanner Maintenance and Calibration 8 by an equal and opposite field in the other direction. The effect of hysteresis is that the trace will be offset from the retrace, as in Figure 92. Figure 92 Scanner hysteresis before correction. The yellow line is the Trace image, and the blue is the Retrace. Other Characteristics Bow During raster scanning, the free end of the scanner moves in an arc over the full range of the scanner, as opposed to a flat line in a plane above the sample.
Scanner Maintenance and Calibration 8 movement) and a single tube for Z motion. Since the range is small with these scanners, the effect of cross-coupling is minimal. Aging Aging is a time-dependent effect in which the sensitivity (extension per unit of field) of the scanner decreases, approximately exponentially, over time. A large amount of decrease takes place during the first few hours of use. Therefore, scanners are burned in before initial calibration.
Scanner Maintenance and Calibration 8 Calibrating the Multi-Purpose Scanner Regular calibration ensures that Agilent multi-purpose scanners will provide high performance imaging for many years of service. The following calibration procedure is recommended once or twice per year, if the system is moved, and before critical measurements. 1 Make sure the correct scanner file is selected under the PicoView Scanner menu. 2 Place a calibration target on a sample plate and mount the plate on the microscope.
Scanner Maintenance and Calibration 8 X Calibration In the Realtime Images window set up two Topography images, one for Trace and one for Retrace (Figure 94). Figure 94 Images of calibration target during Trace and Retrace 6 Choose Scanner > Edit to open the Scanner Setup window.
Scanner Maintenance and Calibration 8 X Non-Linearity To check X non-linearity, in the Realtime Images window choose Tools > Horizontal Cross Section. Use markers to report the dimensions between sets of features at either end of the scan range (Figure 96). Figure 96 Horizontal cross-section tool used to check non-linearity. Two sets of cursors are shown.
Scanner Maintenance and Calibration 8 After updating, re-scan the calibration target. The spacing between features should be approximately the same across the scan range. X Hysteresis Place a vertical cursor at the same location in the Trace and Retrace images. The cursor should cross the same features in both images. If this is not the case, as in Figure 98, increase the X Hysteresis value and re-scan. Alignment should be consistent across the full range of the x-axis.
Scanner Maintenance and Calibration 8 X Sensitivity Using the Cross-section tool, measure the length of a set of features across the scan (Figure 100).
Scanner Maintenance and Calibration 8 the slow scanning axis so the range will be reduced as a time consideration. Only one Topography image is required for Y calibration. The other image can be assigned to display flattened Topography data. Y Non-Linearity Obtain an image of the calibration target. Using the Cross-section tool, set markers at the uppermost and bottommost feature along a vertical cross section (Figure 101).
Scanner Maintenance and Calibration 8 If the dimensions are not identical for the two features, adjust the Y Non-linearity term according to the equation: StartSize CurrentTerm NewTerm = ----------------------------------------------------------------EndSize where StartSize = size of features at the start of the scan EndSize = size of features at the end of the scan CurrentTerm = current non-linear correction term. Use the diagram in Figure 102 as a guide for making the correction.
Scanner Maintenance and Calibration 8 on the edge of a feature while the scan was moving upwards. The red marker was placed on the same feature during the downward scan. Figure 103 Markers indicating trace and re-trace Y hysteresis While scanning in one direction, focus on one step of the grating. As the scan data is plotted position a marker on this edge. Wait for the scan in the opposite direction to occur and position a second marker on the same edge after the plot has been updated.
Scanner Maintenance and Calibration 8 If the measured dimension does not match the actual, the adjust the Y Sensitivity term according to the following equation: CurrentSensitivity Kno wnSize NewSensitivity = ------------------------------------------------------------------------------------MeasuredSize Z Calibration Sensitivity After the X and Y dimensions have been calibrated, obtain an image of a Z calibration standard and render the data as Tilted. Zoom in on a single pit to minimize distortion.
Scanner Maintenance and Calibration 8 top and the bottom of the data plot is flat before making the measurement. If the step size is not within 5 % of the actual value, calculate a new Z sensitivity term using the following equation: CurrentSensitivity Kno wnSize NewSensitivity = ------------------------------------------------------------------------------------MeasuredSize After the X, Y and Z calibration steps have been completed, the scanner is fully calibrated.
Agilent 5500 SPM User’s Guide 9 Closed-Loop Scanners Scanner Types 153 Z-Axis Closed-Loop Scanner 153 X/Y/Z Closed-Loop Scanner 154 Calibration 154 X and Y Sensor Calibration 154 Z Sensor Calibration 158 In an open-loop scanner, a voltage is applied to the piezo actuators in extremely precise increments to move the probe accurately in all three axes.
Closed-Loop Scanners 9 Positional drift that may be present in an open-loop system is continuously corrected with the closed-loop sensor. In the Spectroscopy window you can select the Sensor as Topo check box to use the Z sensor signal instead of the Deflection signal for generating topography images.
Closed-Loop Scanners 9 Figure 106 Scanner Setup window 4 The values shown in Figure 106 for the X, Y and Z Sensor Offset and Gain are typical and represent a good starting point for the calibration process. a Type in the values, and ensure that the Enabled boxes are all checked. b Ensure that the Reversed Gain boxes are checked for X and Z Sensors. c Note that the scanner values will be different for each scanner.
Closed-Loop Scanners 9 7 In the Scan and Motor window enter: a A very large number (e.g., 9999) for the Scan Size. It will adjust automatically to the maximum allowed value. b Speed of 1-2 lines/second. c Resolution of 256. 8 In the Realtime Images window set up two images with the following settings: • Input set to X Sensor. • Flattening set to No Flattening. • Display Range set to 20.000. • Offset set to 0.000. • For one image display Trace and for the other display Retrace.
Closed-Loop Scanners 9 11 Adjust the X Sensor values: a If the line slopes down from the upper left part of the graph, select the Reversed check box in the X Sensor area of the Scanner Setup window. b Adjust the Offset to shift the line up or down until the left end is close to -10 V. c Adjust the X Sensor Gain to adjust the slope until the right end of the line is close to +10 V. The graph should now appear as in Figure 108.
Closed-Loop Scanners 9 17 Adjust the Sensitivity of the X sensor: a In the Realtime Images window choose Tools > Horizontal Cross Section. Place the cross-section tool across a set of features. b Set markers in the cross section window to measure the dimension across several features of known width.
Closed-Loop Scanners 9 of the Z piezo is being measured, adjusting the Z Sensor Gain and Offset should be done without a sample in place. 1 In the Servo window verify that the Z Range of the piezo is set to its maximum value. 2 Choose Controls > Spectroscopy to open the Spectroscopy window (Figure 109).
Closed-Loop Scanners 9 The goal of the calibration procedure is to make the Z Sensor output appear as in Figure 110: Figure 110 Target output of the Z sensor following calibration The plot shows the output of the Z sensor as a function of Z piezo displacement. The Z sensor output ranges from -10 V to +10 V over the entire range of the Z piezo. 5 In the Realtime Images window choose Tools > Enter Range. Set Y Min to -10.0000 and Y Max to 10.0000. The values will adjust to the maximum allowable range.
Closed-Loop Scanners 9 Once the graph looks like Figure 110, the Offset and Gain are properly set and the Z Sensor is usable over its entire range. 8 To calibrate the Z Sensitivity you will need a step height calibration standard (the standard calibration grid supplied with your system will suffice). Its features are 200 nm deep. a Set up the microscope for Contact Mode imaging. b Initiate an approach. c Obtain a 10 micron image centered on one of the calibration standard pits (Figure 111):.
Agilent 5500 SPM User’s Guide 10 MAC Mode List of MAC Mode Components 162 Connections 163 Hardware and Sample Setup 164 The MAC Mode controller provides high precision AC signal control for AAC and MAC modes. The MAC controller uses a lock-in amplifier to generate the AC signal. It also provides routing capabilities and experimental controls for applications requiring additional flexibility in experiment design.
MAC Mode 10 Please contact Agilent if any of these items are missing. Connections The MAC Mode controller is shown in Figure 112. The rear panel is shown in Figure 113. Figure 112 Front panel of the MAC Mode controller Figure 113 MAC Mode controller rear panel The connectors are as follows: 1 MAC drive output. 2 AAC drive output.
MAC Mode 10 3 Input summed to AAC drive signal. 4 Deflection output from detector. 5 Amplitude output from lock-in amplifier. 6 Phase shift signal from lock-in amplifier. 7 To Serial Port on computer. 8 Aux output for custom applications. 9 44-pin cable from AFM Controller. 10 44-pin cable to Head Electronics Box. 11 25-pin cable (if applicable). 12 25-pin cable to HEB (if applicable).
MAC Mode 10 Chapter 6, “AC Modes.” Please refer to Chapter 6 for more on how to set up the microscope for imaging. In AAC Mode the drive signal can be provided by either the Head Electronics Box or the MAC Mode controller. To use the MAC Mode controller as the AC source, choose Controls > Setup > Options, then check the Serial Port AC Mode Controller box. The system will now use the drive signal from the MAC Mode controller, through the HEB to the microscope.
Agilent 5500 SPM User’s Guide 11 MAC III Mode Initial Setup 167 List of MAC III Components 167 Connections 168 Hardware and Sample Setup 171 MAC III Software Controls 171 Simplified Software Control Options Contact Mode 172 AC AFM 172 STM 174 LFM 174 DLFM 174 FMM 175 EFM 177 KFM 180 Advanced Software Control Options Lock-In Tabs 183 Outputs Tab 185 Other Tab 188 171 182 The MAC III controller adds imaging modes, routing capabilities and other experimental controls for applications requiring additional f
MAC III Mode 11 Not only is this arrangement very time efficient, it also ensures that the data is extremely reliable and easy to compare between modes. The MAC III controller is used in conjunction with the AFM controller and Head Electronics Box (HEB). The AFM controller supplies high voltage to the scanner piezo elements. The HEB controls the stage motors and receives information from the photo detector.
MAC III Mode 11 Please contact Agilent if any of these items are missing. Connections The MAC III controller is shown in Figure 114. The rear panel is shown in Figure 115. Figure 114 Front panel of the MAC III Controller.
MAC III Mode 11 In addition to the standard cabling for your microscope, the following connections must be made to use the MAC III in your system. A complete wiring diagram is available in Appendix A. Power Cord Connect the power cord from the back of the MAC III controller to building power. Do not power on the controller at this time. Computer Connection Connect the RS-232 serial cable from the SERIAL port on the MAC III controller to a COM port on your computer.
MAC III Mode 11 cable between the MICROSCOPE connector on the HEB and the 44-pin connector on the microscope base. AFM Controller Connection Connect the longer DB44 cable from the CONTROLLER connector on the MAC III to the PicoSPM II connector on the AFM Controller. BNC 1 and 2 applications. These connectors are user configured outputs for custom AUX The AUX connector has the drive output from each lock-in, a drive-in that can be summed into each lock-in, and an auxiliary input to each lock-in.
11 MAC III Mode summed in to any or all of the drives by using Sum External Drive on the Lock-in tab of the Advanced AC Modes window. SP_RX and SP_TX lines These serial lines are not currently used. Once all connections have been made it is safe to turn on power to all components. Hardware and Sample Setup Most hardware and sample setup options with MAC III are identical to those for standard AAC and MAC Mode operation, as covered in Chapter 6, “AC Modes.
MAC III Mode 11 automatically adjust parameters to appropriate values. The changes will also be visible in the Advanced AC Mode property sheet. In this section we will describe the simplified controls for each mode. Contact Mode Contact mode does not require any MAC III-specific controls. AC AFM In AC mode the drive signal can be provided by either the Head Electronics Box or the MAC III controller.
11 MAC III Mode The following parameters are available in the ACAFM Controls window: Amplitude Displays the amplitude, in volts, of cantilever oscillation. Drive (%) The amplitude of the lock-in drive signal, stated as a percentage (0-100 %) of the maximum available 10 V. Frequency (kHz) Displays the frequency of the lock-in signal. From the AC Mode Tune window you can sweep the frequency of Lock-in 1 to determine the resonance frequency of the cantilever.
MAC III Mode 11 alignment procedure the Pass Through boxes will be selected to allow the correct signals to pass through to the Laser Alignment window. STM STM does not require any MAC III-specific controls. LFM Contact mode does not require any MAC III-specific controls. DLFM In DLFM mode, Lock-in 1 is used to oscillate the tip in the direction of the scan parallel to the sample surface, with the Friction channel as its input. The Drive Mechanism is set to AAC.
11 MAC III Mode Amplitude Displays the amplitude, in volts, of cantilever lateral oscillation amplitude. Drive (%) The amplitude of the lock-in drive signal, stated as a percentage (0-100 %) of the maximum available 10 V. Frequency (kHz) Displays the frequency of the lock-in signal. From the AC Mode Tune window you will be able to sweep the frequency of Lock-in 1, to determine the frequency at which the lateral tip deflection is maximized (i.e., the resonant frequency).
11 MAC III Mode cantilever modulation that results from this applied signal is monitored as a measure of the sample’s elastic properties. Force Modulation is a contact imaging mode and the Deflection signal will be routed to the feedback loop. Choose Mode > Force Modulation, then choose Controls > AC Mode to open the Force Modulation Controls window: Figure 119 Force Modulation Controls window In Force Modulation Mode, Lock-in 1 is enabled, with the Deflection channel as its input.
11 MAC III Mode 10 V, beyond which the signal will be clipped. The default value is x1 (the amplitude times 1). Drive Mechanism The mechanism (AAC, MAC or Top MAC). Zero Phase Sets the phase at the current frequency to zero, making it easier to interpret phase changes from the current value. Q Control On By applying a phase-shifted version of the cantilever drive signal on top of the drive signal, Q control can either increase or decrease the effective quality factor of the system.
MAC III Mode 11 Choose Mode > EFM to open the EFM Controls window: Figure 120 EFM Controls window The Main tab includes settings for Lock-in 1 and Q-Control: Agilent 5500 SPM User’s Guide Amplitude Displays the amplitude, in volts, of cantilever oscillation amplitude. Drive (%) The amplitude of the Lock-in 1 drive signal, stated as a percentage (0-100 %) of the maximum available 10 V. Frequency (kHz) Displays the frequency of the Lock-in 1 signal.
11 MAC III Mode 10 V, beyond which the signal will be clipped. The default value is x1 (the amplitude times 1). Zero Phase Sets the phase at the current frequency to zero, making it easier to interpret phase changes from the current value. Q Control On By applying a phase-shifted version of the cantilever drive signal on top of the drive signal, Q control can either increase or decrease the effective quality factor of the system. Select this box to enable the Q Control feedback loop.
MAC III Mode 11 Optimize Phase shifts the phase signal to maximize the X Component 2 (i.e., to maximize contrast). X Component 2 and Phase 2 are routed to the Aux 1 and Aux 2 outputs, respectively, for monitoring. To view changes in the EFM signal, choose Aux 1 in the Realtime Images window. KFM In KFM Mode, Lock-in 1 is used to drive the cantilever, with the Deflection channel as its Input. Lock-in 2 provides an AC tip bias, also with the Deflection channel as its Input.
MAC III Mode 11 The Main tab shows settings for Lock-in 1 and Q-Control: Amplitude Displays the amplitude, in volts, of cantilever oscillation amplitude. Drive (%) The amplitude of the Lock-in 1 drive signal, stated as a percentage (0-100 %) of the maximum available 10 V. Frequency (kHz) Displays the frequency of the Lock-in 1 signal. From the AC Mode Tune window you can sweep the frequency of Lock-in 1, to determine the frequency at which the tip oscillation is maximized (i.e.
MAC III Mode 11 mechanical response provided by Lock-in 1 and to see if there are any other resonances present. To do so, select the KFM Tune check box, then choose Manual Tune in the AC Mode Tune window. Determining the best frequency for your sample and tip will require some iteration. Two rules typically apply: • The frequency should not be an integral factor of the Lock-in 1 frequency. • The frequency should not be close (within 10-20 kHz) to the Lock-in 1 frequency.
MAC III Mode 11 AC Mode window includes several tabs, each of which is described below. Lock-In Tabs Each of the three lock-ins includes its own tab with the following Settings: Figure 122 Advanced AC Mode Controls window: Lock-in tab Agilent 5500 SPM User’s Guide Amplitude Displays the amplitude, in volts, of whatever is being driven by the lock-in drive. For example, if the lock-in is driving the cantilever, the oscillation amplitude (as measured by the photo detector) is reported.
MAC III Mode 11 an amplitude exceeding 10 V, beyond which the signal will be clipped. The default value is x1 (the amplitude times 1). Bandwidth How far to either side of the selected Frequency the lock-in circuitry is able to process information. Bandwidth can range from 40 Hz to 20 kHz. The default “Automatic” setting will adjust the bandwidth based on the Input signal. Input The source signal that is routed to the input of the lock-in.
MAC III Mode 11 respect to the drive signal (they will remain orthogonal to each other). This feature is useful, for example, to maximize the real component of the drive signal in KFM mode. The default value is 0. Sum External Drive Select this box to add a signal from the AUX input to the lock-in drive signal. By default the box not selected. Y Component from AUX Select this box to add a signal from the AUX input to the Y component of the lock-in drive signal.
MAC III Mode 11 Drive Out Routes the output from one of the three lock-in signals to the circuit controlling oscillation of the cantilever (either AAC or MAC, depending on your setup). Set this option to GND to turn off the output from the MAC III. The default value is Drive 1 (the output from Lock-in 1). Sample Bias The Sample Bias is set in the Servo window and, by default, is sent from the AFM controller to the microscope.
MAC III Mode 11 the box to replace the Ref Set value with the lock-in signal. Select Sum plus GND to pass the Ref Set value from the AFM controller directly to the microscope. These are the default settings. BNC 1 and 2 Each of the Lock-ins includes seven output channels: Deflection, Friction, SP and AUX 1-4. These output signals are routed to the AFM controller. They can also be duplicated at the two BNC connectors on the MAC III controller for additional routing flexibility.
11 MAC III Mode Other Tab The Other tab includes additional parameters that control MAC III operation: Figure 124 Advanced AC Mode window: Other tab Agilent 5500 SPM User’s Guide Drive Selects the drive mechanism (AAC, standard MAC or Top MAC). I Gain The Integral Gain to the MAC III internal servo loop. The default value is 0. P Gain The Proportional Gain to the MAC III servo. The default value is 0. Setpoint (V) The voltage which the servo will try to maintain.
11 MAC III Mode the Q Control feedback loop. By default, Q Control is turned Off. Agilent 5500 SPM User’s Guide Drive (%) Sets the amplitude of the Q Control phase-shifted signal, stated as a percentage (0-100 %) of the maximum available. Phase Shift (°) Shifts the Q Control feedback signal with respect to the input. Sweep Selects the lock-in for which the frequency will be swept on the AC Mode Tune window. Only one lock-in can be swept at a time.
Agilent 5500 SPM User’s Guide 12 Liquid Cell Liquid Cell with Standard Sample Plate Liquid Cell with MAC Mode 193 Flow-Through Liquid Cell 193 191 The liquid cell enables in-situ AFM or STM imaging for better control under realistic environments. The cell is made from chemical-resistant polycarbonate and can be used with a wide variety of liquids. The cell can be used in conjunction with a standard, MAC Mode or temperature control sample plates.
Liquid Cell 12 container; therefore, the sample must be large enough for the O-ring to seat. Figure 125 Liquid cell components Figure 126 Liquid cell mounted on standard sample plate Liquid Cell with Standard Sample Plate One challenge with using the liquid cell is to locate the region of interest through the liquid. It is typically easier to first locate the dry sample and then to add the liquid, as follows: 1 Prepare and place the sample on the sample plate.
Liquid Cell 12 sample are almost touching (i.e., both the tip and sample are close to focus). 4 In PicoView, click the Approach button to place the tip in contact with the surface. 5 Use the video system to locate the region of interest. CAUTION Be extremely careful when moving the scanner while using the liquid cell. Clearance is limited, and contact between the scanner and cell will damage the scanner. 6 Now, in PicoView click the Withdraw button to take the tip out of contact with the surface.
Liquid Cell 12 17 Because of the large movements involved in placing and aligning the liquid cell, you will likely need to adjust both the detector and the scanner position before imaging. Liquid Cell with MAC Mode The procedure for setting up the cell for MAC Mode imaging is similar to that described above. However, the MAC mode sample plate contains a ferrite core that can react when placed in solution or in contact with the sample.
Agilent 5500 SPM User’s Guide 13 Temperature Control Cantilevers for Temperature Controlled Imaging 194 High Temperature Sample Plates 195 Connections 197 Imaging 200 Peltier (Cold MAC) Sample Plate 202 Connections 204 Water Cooling 206 Imaging 207 Tips for Temperature Controlled Imaging 208 Several temperature control sample plates are available for use with the Agilent 5500 SPM. With temperature control, studies can be done while maintaining physiological temperature, for melting experiments, etc.
Temperature Control 13 due to the difference in thermal expansion of the coated and uncoated sides. The bending may adversely affect imaging. High Temperature Sample Plates Two high temperature sample plates are available. The standard hot sample plate (Figure 127) provides a temperature range from ambient to 250 C. Figure 127 Standard hot sample plate The Hot MAC sample plate (Figure 128) provides temperatures from ambient to 110 C and enables imaging in MAC Mode.
Temperature Control 13 The Lakeshore 332 Temperature Controller (Figure 129) drives the high temperature plates. Figure 129 Lakeshore temperature controller CAUTION Agilent 5500 SPM User’s Guide The ramping rate should be keep below 10 degrees per minute to avoid damaging the plate.
Temperature Control 13 Connections Figure 130 shows the three cables included with both high temperature sample plates: Figure 130 High temperature sample plate cables The Hot MAC sample plate also includes a Y connector for the MAC cable (Figure 131). Figure 131 Hot MAC sample stage Y cable. Figure 132 shows the required wiring for the hot sample plate. Figure 133 shows the wiring for the hot MAC sample plate.
Temperature Control 13 connector parallel to the cable and pass it through a port in the chamber. Then screw the round connector into the port to make a tight seal.
Temperature Control 13 Figure 132 Hot sample plate wiring diagram Figure 133 Hot MAC sample plate wiring diagram Agilent 5500 SPM User’s Guide 199
Temperature Control 13 Note that Cable 3 includes a tab on the black-wire side of the connector (Figure 134). The tab must face the Lo jack on the controller. Figure 134 Tab side of Cable 3 must be inserted into the Lo jack. Imaging 1 Set up the microscope for typical operation. As mentioned, uncoated silicon probes are highly recommended. 2 Mount the sample on the sample plate. Do not use double-sided tape to mount the sample because the glue may soften or melt, causing large sample drift.
Temperature Control 13 9 Press the Heater Range button and select Low, Medium or High. CAUTION Do NOT use the High setting with a Peltier (cooling) plate (see below). 10 Press the Setpoint button and enter the desired final temperature. 11 Allow the temperature to stabilize. 12 Initiate an approach. 13 Image as usual. Imaging during temperature ramp is possible provided care is taken to compensate for sample thermal expansion.
Temperature Control 13 Peltier (Cold MAC) Sample Plate The Peltier Cold MAC sample plate lets you image in contact, AAC, MAC or STM Modes at controlled temperatures below or near ambient temperature (Figure 135). The 1X Peltier plate provides a temperature range of -5 to 40 C. Figure 135 Peltier (Cold MAC) sample plate.
Temperature Control 13 The Lakeshore 332 Temperature Controller (Figure 129) is also used with the Peltier plate. The current booster (Figure 136) is used to drive the Peltier sample plate temperature. The booster includes a safety device that shuts off the power if the reverse side of the Peltier becomes excessively hot.
Temperature Control 13 Connections Figure 137 shows the three cables included with the Peltier sample plate: Figure 137 Peltier sample plate cables The Peltier sample plate also includes a special MAC cable for use with MAC Mode (Figure 138).
Temperature Control 13 Figure 139 shows the required wiring for the Peltier sample plate. The connection at the end of Cable 1 enables wiring to the temperature stages through a port in the environmental chamber. Figure 139 Peltier (Cold MAC) sample plate wiring diagram.
Temperature Control 13 Note that Cable 3 includes a tab on the black-wire side of the connector (Figure 140). The tab must face the Lo jack on the controller. Figure 140 Tab side of Cable 3 must be inserted into the Lo jack Water Cooling When a sample is cooled using the Peltier sample plate the opposite side of the Peltier device becomes hot. The hot side is water cooled to decrease the minimum sample temperature, reduce power requirements and prevent overheating.
Temperature Control 13 Figure 141 Gravity-fed water cooling system for Peltier sample plate. Imaging 1 Set up the microscope for typical operation. As mentioned above, uncoated silicon probes are highly recommended. 2 Mount the sample on the sample plate. 3 Set the Range control on the current booster to its minimum setting (fully counterclockwise). 4 Set the current booster to 1X. 5 Turn on the Lakeshore controller and current booster.
Temperature Control 13 11 On the Lakeshore controller press Heater Range and select Low. 12 Press the Setpoint button and enter the desired final temperature. 13 Allow the temperature to stabilize. 14 Initiate an approach. Tips for Temperature Controlled Imaging • Make sure there is good thermal contact between the sample and the sample plate. If possible, mount the sample using the liquid cell even for ambient imaging. • Double-sided tape reduces thermal conductivity as well as introducing sample drift.
Agilent 5500 SPM User’s Guide 14 Environmental Control Environmental Chamber Glove Box 212 209 In addition to the vibration isolation chamber mentioned earlier in this User’s Guide, two other options are available to let you control the atmosphere for sample preparation and/or imaging. Environmental Chamber The environmental control chamber (Figure 142) lets you isolate samples for imaging in a controlled atmosphere.
Environmental Control 14 atmospheric pressure and is not intended to provide a vacuum or high pressure environment. Figure 142 Environmental chamber The environmental chamber includes eight ports which may be used to introduce or remove gases from the chamber, or to allow wiring access for sensors or other electronics. Several types of screw-in fittings are available from Agilent for wires, liquids or 3 mm (1/8 in) inner diameter gas tubing. The ports can be used in any combination.
Environmental Control 14 microscope base will fit into grooves in the environmental chamber base. 5 Swing the microscope back down over the environmental chamber. A groove in the underside of the microscope plate provides a tight seal with the gasket on the top of the chamber (Figure 143). Figure 143 Environmental chamber on microscope 6 Secure the environmental chamber to the base plate with the four thumb screws (two in front, two in the rear).
Environmental Control 14 environmental chamber through a hole in the side of the vibration chamber. Glove Box The glove box lets you create a controlled environment for both sample preparation and imaging. As with the environmental chamber, the glove box includes eight ports for introducing gases, liquids or wires into the chamber. The clear acrylic box is 244 mm (9.6 in) high, 325 mm (12.8 in) wide and 351 mm (13.8 in) deep and can be used at temperatures below 0C.
Agilent 5500 SPM User’s Guide 15 Electrochemistry Equipment 216 Liquid Cell 216 Electrodes 216 Working Electrode and Pogo Electrode Reference Electrode 217 Counter Electrode 217 Cleaning 218 Liquid Cell Cleaning 218 Non-Critical Applications 218 Critical Applications 218 Electrode Cleaning 219 Sample Plate Cleaning 219 Substrate Cleaning 219 Assembling and Loading the Liquid Cell 219 Troubleshooting 220 Electrochemistry Definitions 220 Software Controls 221 Potentiostat 221 Galvanostat 222 216 The electr
Electrochemistry 15 electrochemistry experiments can be conducted using either AFM Modes or STM Mode. NOTE Agilent 5500 SPM User’s Guide As of the writing of this manual, electrochemistry requires PicoScan software. An upcoming release of PicoView software will also include electrochemistry functionality.
Electrochemistry 15 Figure 145 Electrochemistry experiment schematic Figure 146 Electrochemistry experimental setup using liquid cell Agilent 5500 SPM User’s Guide 215
Electrochemistry 15 Equipment The equipment needed to perform electrochemistry experiments can be as simple as a liquid cell and electrodes, or as complex as a flow-through pump system with a temperature-controlled sample stage. The basic components are described below. Liquid Cell The liquid cell, described earlier in this manual, enables imaging in a liquid (Figure 145). The cell is 15 mm (0.59 in) in diameter and seals over the sample with an o-ring.
Electrochemistry 15 Reference Electrode The reference electrode (RE) should have a diameter of 0.51 mm (0.02 in). It will sit within the electrolyte but will not contact the working electrode (sample). Figure 148 Reference electrode Counter Electrode The counter electrode (CE) is typically made from platinum-iridium wire (Figure 149). It should encompass as much of the inner rim of the liquid cell as possible.
Electrochemistry 15 Cleaning Thorough cleaning of all components will greatly improve the results of electrochemistry experimentation. Suggestions for cleaning each component are given below. Liquid Cell Cleaning The liquid cell should be cleaned prior to every use according to these instructions: Non-Critical Applications 1 Sonicate the liquid cell in laboratory detergent. 2 Rinse in 18 MW/cm water. 3 Rinse in methanol. 4 Blow dry under argon or nitrogen gas.
Electrochemistry 15 Electrode Cleaning Electrodes should be carefully cleaned prior to assembling the liquid cell. This may even include flame annealing of the electrodes prior to use in certain cases. Sample Plate Cleaning Since the sample plate does not directly contact the sample surface or electrolyte, a general cleaning with methanol or ethanol prior to assembly is sufficient. Substrate Cleaning Substrates should be free of surface contaminants.
Electrochemistry 15 8 Insert the counter and reference electrodes into the sample plate block (Figure 146). Push the spring-loaded clamp forward from behind, insert the electrode and release the clamp. 9 Position the electrodes so that they will make good contact with the electrolyte but will not touch the sample substrate or each other. 10 Use a multimeter to check for good conductivity between the reference electrode and sample plate clamp, and between the counter electrode and sample plate clamp.
Electrochemistry 15 operational amplifier, but the tip itself is not connected physically to ground. 2 In AFM Mode the potential of the tip is determined by the setting of the switch on the back of the Head Electronics Box (for conductive cantilevers): a If the switch is set to WE then the cantilever is biased to the same potential as the working electrode (sample substrate). b If the switch is set to Tip then the cantilever is tied to the tip bias DAC output.
Electrochemistry 15 bias, probe potential and sample potential. Any one of these potentials can be swept during cyclic voltammetry in the software. In the most common configuration: a Set the sample potential initially to the open circuit potential (i.e., the potential of the cell with the counter electrode turned off). b Set the sample potential to be swept. c Fix the sample bias at an appropriate value for the image mode selected.
Agilent 5500 SPM User’s Guide Appendix A Wiring Diagrams Agilent 5500 SPM Standard Wiring Diagram 224 Agilent 5500 SPM with MAC Mode Controller 225 Agilent 5500 SPM with MAC Mode, Force Modulation Imaging 226 Agilent 5500 SPM with MAC III Option 227 Agilent 5500 SPM with MAC III Option and Closed Loop Scanner 228 The following pages contain wiring diagrams for several common configurations of the Agilent 5500 SPM.
A 224 Agilent 5500 SPM Standard Wiring Diagram Wiring Diagrams Agilent 5500 SPM User’s Guide Figure 150 Wiring diagram for Agilent 5500 standard configuration
A 225 Agilent 5500 SPM with MAC Mode Controller Wiring Diagrams Agilent 5500 SPM User’s Guide Figure 151 Wiring diagram for Agilent 5500 SPM with MAC Mode Option
A 226 Agilent 5500 SPM with MAC Mode, Force Modulation Imaging Wiring Diagrams Agilent 5500 SPM User’s Guide Figure 152 Wiring diagram for Agilent 5500 SPM with MAC Mode Option, Force Modulation imaging mode
A 227 Agilent 5500 SPM with MAC III Option Wiring Diagrams Agilent 5500 SPM User’s Guide Figure 153 Wiring diagram for Agilent 5500 SPM with MAC III Option
A 228 Agilent 5500 SPM with MAC III Option and Closed Loop Scanner Wiring Diagrams Agilent 5500 SPM User’s Guide Figure 154 Wiring diagram for Agilent 5500 SPM with MAC III Option and Closed Loop Scanner option
Index Index A D AAC Mode, 103, 130 AC Mode, 24, 103, 113 Acoustic, 25, 103, 104, 130 Constant height, 109 Magnetic, 26, 103 Top MAC, 112 AC Mode Tune window, 105, 106 ACAFM, 25 Acoustic AC Mode, 25, 103, 104 Acoustic noise, 55, 56 Adhesion, 18 adhesion, 29 Adhesive force, 23 AFM, 21 Aging, 142 Air flow, 55 Amplitude, 25 Approach, 95, 96, 108, 118, 126, 132 Approach Range, 96 Atomic Force Microscopy, 21 Auto Tune, 107, 131 Deflection, 19, 22, 99, 121 Deflection signal, 80 Desiccator, 139 Detector, 22, 40
Index G Gains, 96, 108, 154 Optimizing, 101 Glove box, 212, 219 MAC Mode controller, 26, 27, 30, 31, 103, 110, 127, 162, 163, 165 Magnetic AC Mode, 26, 103 Manual Tune, 126 Microscope base, 80 Multi-purpose Scanner, 114, 119, 127, 139, 143 H N Head Electronics Box, 81, 93, 124, 162, 167, 221 HEB, 81, 93, 124, 162, 167, 221 Hot MAC sample plate, 195, 197, 199 Hot sample plate, 195, 197, 199 Humidity, 57 Hysteresis, 140, 146, 149 Nano-manipulation, 19 Non-linearity, 140, 145, 148 Nose assembly Care and
Index Reference electrode, 217, 220 Requirements Acoustic noise, 56 Resolution, 97 Retrace, 141, 144 S Sample plate, 216 Cleaning, 219 CSAFM, 120 Hot, 195, 197, 199 Hot MAC, 195, 197, 199 MAC, 111 Peltier Cold MAC, 202, 204, 205, 206 STM, 117 Scan Initiate, 98 Number of frames, 100 Stop a scan, 100, 109 Scan and Motor window, 97, 108, 118 Scan settings Frames, 109 Offset, 97 Offsets, 108 Optimizing, 101 Resolution, 97 Scan size, 108 Size, 97 Speed, 97, 108 Scanner Aging, 142 Bow, 141 Calibration, 143, 152
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