Instruction manual

Electric Force (EFM) Imaging

Electric Field Gradient Detection—Procedures

258 MultiMode SPM Instruction Manual Rev. B

Figure 14.4c Shift in Phase at Fixed Drive Frequency

• Under Interleave Controls set the Lift start height to 0nm, and Lift scan height to

100nm. (The lift height can later be optimized.) Set the remaining Interleave parameters

(Setpoint, Drive amplitude, Drive frequency, and gains) to the main Feedback

Controls values. This can be done by setting the ﬂags (left of the Interleave Control

column) to “off” (grayed bullets). Set the Analog 2 to 1V (this will be optimized later).

• Quit Auto Tune and return to Image Mode

• Engage the AFM and make the necessary adjustments to obtain a good topography

(Height) image on Channel 2.

• Select the Interleave Controls panel. Set the Setpoint, Drive amplitude, Drive

frequency to Main (“off” grayed bullets). Verify that Interleave scan is set to Lift.

• Choose a Lift scan height of 100nm. This will be optimized later. Set the Channel 1

image Data type to Phase and choose Retrace for the scan Line direction on both

Channel 1 and 2 images.

• Switch Interleave mode to Enable to start LiftMode. Set the Channel 1 Scan line to

Interleave to display interleave data. This screen should now display the cantilever

phase change due to electrical force gradients from the sample in the left image and

topography in the right image.

• Optimize the Lift height. For high-resolution, make the Lift scan height as small as

possible without crashing the tip into the surface. If the tip crashes into the surface it

creates bright or dark streaks across the image. Also, if the Lift scan height is set

extremely low, the tip may continuously “tap” on the surface during the LiftMode scan.

Check this by toggling between the Interleave and main scan lines for the phase image.

The two images will look very similar if the tip is continuously tapping on the surface

during the LiftMode scan. In this case, increase the Lift scan height until the

Interleave scan image abruptly changes, indicating that it is now oscillating above the

surface and not continuously tapping.

∆φ

Drive Frequency

180

Phase (deg)

∆F