PREPARING THE NANOSCOPE
1. Choose desired tip, making note as to which tip is used.
2. Check under table-mounted optical microscope to ensure that tip is not broken.
3. Turn on the computer, video screen, monitors, nano-scope, microscope light, and
table air-pump (flip the switches/press the buttons). Turn on the microscope light
to a low setting of the dial and keep it low throughout measurements to avoid
burning out the bulb.
4. If the computer waits for input in DOS, type z and ENTER.
5. Once booted, click the Microscope icon on the far left of the left computer
monitor to be in nano-scope mode.
6. Mount tip onto the U-shaped tip holder using tweezers. Note which tip holder
used (perhaps by the color of the metal lever holding onto the tip).
7. Check again that tip is not broken.
8. Tighten screw on the right of the DI laser (releases the laser).
9. Carefully slide the laser out of its mount and lay it sideways on top of the black
vacuum chamber.
10. Remove any tip and tip holder currently on the laser and safely put it away.
11. Place new tip holder on the laser.
12. Carefully replace laser on its mount.
13. Loosen the screw to secure the laser.
14. Use the screws on the top of the laser to adjust the beam onto the tip.
15. Look at the right monitor and try to align the red dot in the middle of the
crosshairs.
16. Make sure the sum is roughly 2 or greater (depending on the tip).
17. Move the up-down screw to check that the red dot vanishes quickly. If it does,
most likely you have found the tip.
18. Use the screws on the left side of the laser to fine-tune the position of the red dot
in the cross hairs.
19. Locate Tip by clicking the rightmost icon on the left computer monitor; a Locate
Tip dialogue box will appear.
20. Adjusting the screws on the video camera, center the crosshairs of the video
monitor just right of the tip end.
21. Click Zoom In on the dialogue box; focus the tip by pressing the lower-left button
and rolling the ball-joystick up/down. Pressing the top-left button simultaneously
will lock the camera into a continuous focusing rate. Click OK.
22. Tune the tip by clicking the tuning fork icon (fifth from the right on the left
monitor).
23. On the Auto Tune Controls dialogue box, set an adequate frequency scan range
(adjusting Start and End Frequency) that contains the drive frequency of the tip as
indicated on the box whence the tip came.
24. Click Auto Tune in the Auto Tune Control box.
25. Still in the Auto Tune Controls box, set the target amplitude at the highest
possible level that does not induce a “Safety Limit” error message. Start at 3 V
and lower appropriately.
26. Click Offset on the right monitor menu bar and move the vertical dashed line
slightly off the maximum point of the resonance curve, where the curve develops
a noticeable slope.
27. Click Execute on the right monitor menu bar.
28. Click Zero Phase on the left monitor Channel Two dialogue box.
29. Click Back to Image Mode on the Auto Tune Controls dialogue box or the Eye
icon on the upper-right of the left monitor.
30. Carefully place desired sample on the stage and rotate stage until sample is under
the laser. Be careful to avoid a collision between the sample and tip.
31. Click the Find Surface icon on the left monitor (second from right); a Find
Surface dialogue box will appear.
32. Clicking only the top-left button on the joystick, roll the ball to move the stage
and center the sample under the microscope.
33. Click Zoom In on the left monitor and focus the sample using ball-joystick
(clicking bottom-left button of joystick). Click OK on the Focus Surface dialogue
box.
34. Fine tune the orientation of the sample by slowly rotating the stage, i.e. the
preferred x-axis/y-axis on the sample should align appropriately with the
crosshairs on the video screen.
35. Check the scan parameters in the Scan Controls box on the left monitor and insure
the tip velocity is not over 40 microns/sec.
TAKING AN AFM IMAGE
1. Under Microscope on the left monitor menu bar, click Profile to choose desired
microscope mode (Contact AFM or Tapping AFM). Click Load.
2. Click the Engage icon (leftmost on left monitor) to lower tip to sample and begin
measurement.
3. After the tip has engaged the surface, click the Scope Trace icon (fourth from left
on left monitor).
4. In the Feedback Controls window of the left monitor, manipulate the
Proportional- , Look-ahead- and Integral Gains (usually lowering) to smoothen
the scope trace curves. Manipulate the Amplitude Set-point (usually lowering) to
overlap the trace and re-trace lines. Be careful that the Set-point not fall too low.
5. For topographical image, Data Type of Channel 1 should be set to Height. For
AFM Mode, set the Data Type for Channel Two off, unless necessary.
6. To locate position on the sample, set a high Scan Rate with low resolution
(Sample/Line) over a large Scan Size to make a rough image of the sample.
Again, be careful not to exceed 40 microns/sec in tip velocity.
7. Once correctly oriented, change X/Y Offsets to fine-tune the position of the tip
over the sample.
8. Check image by clicking the Image icon (third from the left on left monitor).
9. Choose a preferred Scan Angle and Scan Size depending on the nature and
orientation of the sample.
10. When satisfied with position of the tip, change Sample/Line to 512 to improve
resolution.
11. Recheck the scope trace and insure nice and overlapping trace and retrace curves.
Lowering the Scan Rate under Scan Controls and manipulating the Integral-,
Look-ahead- and Proportional Gains and Amplitude Set-point in Feedback
Controls can improve any flawed curves.
12. Click Capture on the left monitor menu-bar and choose Capture to save the next
completed scan (bottom of the left monitor will read Capture: On). Choosing
Continuous will capture all subsequently scanned images until aborted (bottom of
screen will read Capture: Movie). You can click Abort under the Capture menu
at any time to cancel the saving of an image.
13. To access any saved image at any time, click the wavy rainbow icon on the right
of the left monitor. Analyzing data will not stop the capturing of an image. To
return to Microscope mode from the Analyze Data mode, click the rightmost
microscope icon
14. When done imaging, click the Disengage icon (second from left on the left
monitor). This will pull the tip away from the surface. Clicking twice will create
a safe distance between the sample and tip to remove the sample from the stage (if
desired).
15. Now you can analyze saved images or remove the tip and shut off the machine.
16. To shut off the machine, click the DI logo in the top left of the screen and choose
END; switch off all appropriate switches.
TAKING AN MFM IMAGE
1. For an MFM image, follow the steps under Preparing the Nanoscope with the
following alterations:
a) Before mounting tip holder onto the laser, make sure you are using a magnetic
tip. Magnetize the tip by resting a magnet near its surface (DI provides a
specially shaped magnet for just the occasion).
b) Before mounting the sample on the stage, magnetize the sample in the
preferred orientation.
c) Follow the rest of the instructions as specified by Preparing the Nanoscope.
2. Under Microscope on the left monitor menu bar, click Profile and choose MFM.
Click Load.
3. Under the Interleave Controls box, make sure Interleave Mode is set to Disabled.
Set Lift Start Height around 100 nm and Light Scan Height around 70 nm.
4. Under Channel 1, set Data Type to Height. Under Channel 2, set Data Type to
Phase.
5. Click the Engage icon (leftmost on left monitor) to lower tip to sample and begin
measurement.
6. After the tip has engaged the surface, click the Scope Trace icon (fourth from left
on left monitor).
7. In the Feedback Controls window of the left monitor, manipulate the
Proportional-, Look-ahead- and Integral Gains (usually lowering) to smoothen
the scope trace curves. Manipulate the Amplitude Set-point (usually lowering) to
overlap the trace and re-trace lines. Be careful that the Set-point not fall too low.
8. To locate position on the sample, set a high Scan Rate with low resolution
(Sample/Line) over a large Scan Size to make a rough image of the sample.
Again, be careful not to exceed 40 microns/sec in tip velocity.
9. Once correctly oriented, change X/Y Offsets to fine-tune the position of the tip
over the sample.
10. Check image by clicking the Image icon (third from the left on left monitor).
11. Choose a preferred Scan Angle and Scan Size depending on the nature and
orientation of the sample.
12. When satisfied with position of the tip, change Sample/Line to 512 to improve
resolution.
13. With a satisfactory topographical image forming, you are now ready to begin
MFM measurement. Switch Interleave Mode to Lift in the Interleave Controls
box.
14. Recheck the scope trace and insure smooth and overlapping trace and retrace
curves for both channels. Lowering the Scan Rate under Scan Controls and
manipulating the Integral-, Look-ahead- and Proportional Gains and Amplitude
Set-point in Feedback Controls can improve any flawed Channel 1 curves. The
Channel 2 curves are indirectly affected by these manipulations as well.
15. Click Capture on the left monitor menu-bar and choose Capture to save the next
completed scan (bottom of the left monitor will read Capture: On). Choosing
Continuous will capture all subsequently scanned images until aborted (bottom of
screen will read Capture: Movie). You can click Abort under the Capture menu
at any time to cancel the saving of an image.
16. To access any saved image at any time, click the wavy rainbow icon on the right
of the left monitor. Analyzing data will not stop the capturing of an image. To
return to Microscope mode from the Analyze Data mode, click the rightmost
microscope icon
17. When done imaging, click the Disengage icon (second from left on the left
monitor). This will pull the tip away from the surface. Clicking twice will create
a safe distance between the sample and tip to remove the sample from the stage (if
desired).
18. Now you can analyze saved images or remove the tip and shut off the machine.
To shut off the machine, click the DI logo in the top left of the screen and choose
END; switch off all appropriate switches.
SURFACE SCANNING POTENTIAL MEASUREMENT
1. For an SPM image, follow the steps under Preparing the Nanoscope with the
following alterations:
a) Configure the jumpers on the back of the microscope in the electronics box,
carefully removing the cover plate. Examine the figures in the reference
manual (Chapter 14) and identify which jumper configuration is appropriate
for your application. Different jumper configurations are necessary for
applying a voltage directly and indirectly to the sample (figures 14.24 and
14.23 respectively).
b) Mount a sample onto the stage. Make any external electrical connections
necessary for the sample. Using a simple AA battery configuration is
adequate.
c) Locate the two toggle switches on the backside of the Extender Electronic Box
(figure 14.25). Set the Mode switch to Surface Potential and Tip or Sample
Voltage switch to GND/Surface Potential.
d) Mount a metal-coated tip into the electric field cantilever holder. MFM tips
usually work well, but it is also possible to deposit custom coatings on model
silicon Tapping Mode tips.
e) When tuning the cantilever, remember that the Extender Box has been
reconfigured so that the phase detection circuitry now acts as a lock-in
amplifier. Any procedures that are normally used to view or adjust the phase
signal will now affect the lock-in signal instead (refer to figure 14.21).
f) Follow the rest of the instructions as specified in Preparing the Nanoscope.
2. Choose the mode of measurement: under Microscope on the left monitor menu
bar, click Profile and choose Surface Potential. Click Load.
3. Engage the AFM and make the necessary adjustments for a good Tapping Mode
image while displaying height data.
4. Select the Interleave Controls command. This accesses a new set of scan
parameters that are used for the interleave scan where surface potential is
measured. Set the Drive Frequency to the main feedback value. Enter an
interleaved Set-point of 0V. Set Interleave Scan to Lift.
5. Enter an Interleave Controls Drive Amplitude. This is AC voltage applied to drive
the tip on the second (SPM) trace. A large Drive Amplitude reduces the range of
the DC voltage that can be applied to the tip. To start, set this to 5V.
6. Set the Channel 2 image Data Type to Potential. Set the scan Line Direction for
the main and interleave scans to Retrace. This is done because the lift step occurs
on the trace scan and data collection occurs on the retrace.
7. Choose a Lift Start Height of 0 nm and a Lift Scan Height of 100 nm. The Lift
Scan Height can be readjusted later.
8. Switch Interleave Mode to Enable to begin Lift Mode. When the microscope
completes a topographical scan line (trace and retrace), the system turns off the
Tapping Mode piezo and switches the oscillator signal to the tip. The tip is then
driven electrostatically according to the selected interleave Drive Amplitude.
When Potential is selected as the Data Type for the Channel 2 image, a feedback
circuit is enabled in the Extender Box whish adjusts the DC voltage on the tip to
maintain the tip oscillation amplitude at zero.
9. Adjust the FM gains. In the Feedback Controls window of the left monitor,
manipulate the Proportional-, Look-ahead- and Integral Gains (usually lowering)
to smoothen the scope trace curves. Manipulate the Amplitude Set-point (usually
lowering) to overlap the trace and re-trace lines. Be careful that the Set-point not
fall too low.
10. Optimize the Lift Heights by setting Lift Scan Height to the smallest value
possible that does not make the Potential feedback loop unstable or cause the tip
to crash into the sample surface.