Chapter 7. Performing Measurements
161
7.6.2. I(Z) Spectroscopy
I(Z)–spectroscopy uses the relation between the tunneling current (IProbe signal) and
extension of the Z-scanner (parameter Height).
With the relation between the tunneling current and the distance the scanner tube is
extended to, sharpness of the tip can be evaluated.
To making measurements, perform the following:
1. Verify that the controller is configured for STM measurements (Fig. 7-141).
2. Open the spectroscopy window by clicking the button.
3. In the Spectroscopy Mode drop-down list, select I(Z) STM. This will result in:
● selecting the IProbe signal as a recorded signal in the Measurements panel;
● selecting the Height signal as the argument of the measured relation in the
Argument panel.
Redefine the set of measured signals, if necessary.
4. In the fields From and To, define the variation range of the argument of the measured
relation.
5. Define the desired limits for a signal if necessary.
6. In the Speed group, adjust speeds of taking 1D relations at forward (Forw parameter)
and backward (Back parameter) scanning.
NOTE. The recommended duration of the forward scan is
∼
~ 5 sec.
7. Select the mode of defining the spectroscopy points (by points, by a line, or by a grid)
and define the points.
8. Launch measurements by clicking the button .
When the measurements complete, the Viewing Area displays a plot for the last
measurement point. An example of the I(Z) Fig. 7-151.
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