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MEASUREMENT OPERATION
5-154
TMPM5200-2
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CITS image observation
A CITS (Current Imaging Tunneling Spectroscopy) image is a tunneling-current image
produced when applying an optionally designated bias voltage while keeping the
distance between the tip and the specimen surface (determined by the topographic-image
observation conditions such as tunneling current and bias voltage) constant. I-V curves
and data averaging at designated points on the specimen can also be obtained from the
image captured in the CITS menu. In the case of CITS, unlike STS, I-V data is measured
and an image is created at each pixel during tip scanning, so there is no influence of
specimen drift or hysteresis so that the I-V curve at an arbitrary point of the image
perfectly corresponds to the image points.
Tip
I-V
I-V measurement
cur
ev
ve is measured at
er y pixel
128 points
15 points standar
128 points
d)
V
I
elect a point where the image contrast varies greatly on an STM image and measure an
once; then select the bias voltage of the position where the I-V
.
Click on the SPS button on the Advanced tab window of the SPM Parame-
s window will appear.
One method of determining the bias voltage is as follows.
S
I-V curve at that point
curve varies greatly.
CITS measurement parameters such as Low Voltage and High Voltage are the same as
those set in the SPS Parameters window.
Observe a CITS image using the following procedure.
1
ters window.
The SPS Parameter
2.
Click on the
3.
Specify the parameters for I-V measurement according to the following
procedure.
IV tab.
