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Software Selection

You may perform SCM measurements either open loop or closed loop.

  1. Click the Select Experiment icon in the NanoScope toolbar. This opens the Select Experiment window, shown in Figure 1.

Figure 1: The Select Experiment, SCM mode, window.

  1. Select Electrical & Magnetic in the Experiment Category panel.
 
  1. Select Application Modules in the Experiment Group panel.
  2. Select Scanning Capacitance Microscopy (SCM) in the Select Experiment panel.
  3. The Feedback and SCM panels, shown in Figure 2, in the Scan Parameter list display the SCM control parameters.

Figure 2: SCM control parameters in the Scan Parameter list

  Table 1 summarizes the functions of the parameters in the SCM controls panel of the Scan Parameters window.
Parameter Use with SCM
SCM Feedback Disabled: open loop. Enabled: closed loop (i.e., Constant Depletion SCM Mode, feedback on dC/dV amplitude).
AC Bias Amplitude Amplitude of the AC bias applied to the sample.
Bias Frequency Frequency of the AC bias applied to the sample.
Aux Lock-In BW Bandwidth of the Auxilary Lock-In
SCM Lock-In Phase Phase of the SCM lock-in amplifier with respect to the reference bias frequency.
DC Bias DC bias applied to the sample.
Capacitance Sensor Frequency The frequency of the oscillation within the scan sensor.
SCM Igain Integral gain used for closed-loop mode.
SCM Pgain Proportional gain used for closed-loop mode.
Feedback Setpoint Not used in open loop mode. Selects the dC/dV setpoint in closed-loop mode.
Feedback Limit Limits the bias amplitude in closed-loop mode.

Table 1: SCM Control parameters

NOTE: Due to inherent mechanical characteristics of the specialized probe holder necessary for this imaging mode, reduced closed loop X IGain and Y IGain parameters are necessary.
  1. Select Calibrate > Scanner > X-Y... from the main menu. The OptoXY Closed Loop Calibration dialog will open.
  2. Set X IGain and Y IGain to 8.
  3. Click OK to close the window and continue with your experiment.

Ensure that you reset the parameters to their default values (12) when using the standard air tapping or TR holder.

 

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