Set Up the Generic Lock-In Interface

The following steps show how to get Vertical and Horizontal Piezoresponse data using the Generic Lock-Ins. This procedure is not necessary for PFM Optimized Vertical Domains Operation.

The example experiment below was performed on a PZT thin film. While the PPLN sample may show lateral contrast, the interpretation of the contrast is difficult. To map the lateral domains simultaneously with the vertical domains, the Generic Lock-In feature using two lock-ins simultaneously will be used. Orient the sample so that the domains are parallel or perpendicular to the tip scan direction.

1. Select Microscope > Generic Lock-In from the main menu to open the Generic Lock-In window:

2. On the Lock-In1 tab, ensure that Lock-In 1 is Enabled.
3. Set the Drive Routing to Sample (default).The drive can also be routed to the tip. However, for this example we chose to use the Drive Routing to the sample.
   NOTE: For operation at frequencies greater than 150 kHz, use front panel drive from DDS1 or DDS2.
4. Set the following parameters:
   • Drive Amplitude: 10000 mV
   • Drive Frequency: < 100 kHz
   • Lock-In1 Source: Vertical (to map c-domains in a piezoresponsive sample, one is interested in the vertical motion of the cantilever, hence the choice of Vertical for the source)
5. In the Generic Lock-In window, select the Lock-In2 tab:

6. Ensure the Harmonic is set to 1 (first harmonic) in the drop down list. This ensures that the lock-in uses the fundamental vibration mode for capturing the data.
   NOTE: This measurement is also being performed with the data from the main line.
7. Ensure the Lock-In2 Source is set to Horizontal. This enables the lock-in to use the lateral deflection signal and map the lateral domains in the PZT thin film.
8. The NanoScope software with the generic lock-in interface allows the user to apply a Lateral 16X Gain. In the Scan Parameter List, under Feedback parameters, set the Lateral 16X Gain to Enabled.

9. To improve the deflection signal, change the Scan Angle to 90 degrees and reduce the Scan Rate to 0.3 Hz in the Scan Parameter List:

10. Set the data channels:

11. Click either frame-up or frame-down and proceed to capture an image.

Below, the Amplitude1 and Phase1 channels show the vertical domains in the PZT film. The Amplitude2 and Phase2 channels show the lateral domains in the film.

Sometimes, scanning the surface at a 45 degree scan angle may reveal more details than scanning at either 90 or zero degrees. The image below shows a 45 degree scan angle of the same PZT filmfrom above.

The Generic Lock-In can also be used to map the surface using higher harmonics. See Working With Higher Harmonics Using Generic Lock-Ins for details.

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