Procedure for Nanoindenting

1. Click the Select Experiment icon to open the Select Experiment window.

2. Select the following:
   • Experiment Category: Mechanical Properties
   • Experiment Group: Nanoindentation
   • Select Experiment: Nanoindentation

3. Click Load Experiment.
4. Set up the system for Basic TappingMode Operation. Note the following when setting up for Nanoindentation:
   • First time nanoindentation users should use the soft gold film sample
   • The resonant frequency is in the range of 35–70 kHz for indentation probes. Set the Drive frequency at the center of the resonance peak.
   • Adjust the Drive amplitude until the RMS amplitude of the cantilever is from 100–250 mV (this is significantly lower than the RMS amplitude typically used with standard TappingMode probes).
   • The Scan Rate should be limited to about 1 Hz for indentation cantilevers.
   • Engage with a small Scan Size, about 1 μm or less, and increase the Scan size after engaging if necessary.
   • Set the initial Integral gain to 0.5 and the Proportional gain to 5.0.
   • The SPM safety parameter in the Engage Parameters window is set (by default) to at least 200 μm to ensure the tip does not become damaged during the engage.

5. Execute the Engage command.

6. Image the surface:
   • Lower the amplitude Setpoint just enough to ensure that the tip is tracking the surface.
   • Locate a site at which indenting is desired. Note that indentations will be made in the center of the current scan.

1. Click the Ramp button in the workflow toolbar to enter Ramp mode.

2. Ensure that the Start Mode parameter is set to Indent (this is the default for the Nanoindentation workspaceA collection of views and parameters organized for a specific imaging mode. Workspaces create an environment tailored to the selected imaging mode and give the user a start in the right direction toward optimizing imaging parameters.).

The Ramp Parameter List will display menu items specific to Nanoindentation, including the Indent and Auto panels. First time users can use the Indent panel parameter values as shown in Figure 1 as a guide for parameter settings for nanoindentation. These settings are a good starting point whenever indenting on a new and unknown sample.

3. Set the Trigger threshold.

Before making an indentation, it is necessary to set the force applied to the tip. This is set using the Trigger threshold parameter, abbreviated "Trig threshold", located in the Indent panel. The Trigger threshold, specified in volts, is the cantilever deflection at which the controller stops pushing the tip into the surface. It is a measure of the force applied to the sample during indentation. A good starting value is 100 mV.

4. Execute an indentation. To make an indentation in the surface, click on the Start Single Ramp button. The tip will be plunged into the surface and a force plot will appear on the scope window.

5. To capture the force plot generated to the capture directory, click on the Capture button. An example force plot is shown in Figure 2, for a Trigger threshold of 0.9 V. The force plot is a graph of the cantilever deflection versus the Z movement of the scanner.

1. Return to the Scan view and image the indentation. The system will return to TappingMode imaging and the indentation may be viewed. Use a Scan size of 1–3 μm to image the indentation.

2. If the indentation is not visible on the sample surface, return to the Ramp view and execute another indentation with a larger Trigger threshold. Increase the Trigger threshold by 50–100 mV increments until indentations are visible on the sample surface. It will be necessary to increase the ramp size.