JEOL JSPM-5200 Instructions Manual page 217

５ MEASUREMENT OPERATION
■ 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.
128 points
One method of determining the bias voltage is as follows.
S elect a point where the image contrast varies greatly on an STM image and measure an
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 .
Click on the SPS button on the Advanced tab window of the SPM Parame-
ters window.
The SPS Parameter
2.
Click on the
3.
Specify the parameters for I-V measurement according to the following
procedure.
5-154
Tip
I-V cur ve is measured at
128 points
once; then select the bias voltage of the position where the I-V
s window will appear.
IV tab.
I-V measurement
I
ev ery pixel
15 points standar
V
d)
TMPM5200-2