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MEASUREMENT OPERATION
5-134
TMPM5200-2
rameter that determines the scan speed. Naturally, this parameter
Bias
This is the pa
should be changed according to the observation area and the unevenness of the
specimen.
/V
Click on the Bias/V box and when the numerical value is highlighted, enter 1
using the keyboard; then press the Tab key to finalize the value.
It is necessary to change Bias/V depending upon the specimen.
Normally, for specimens with high electrical conductivity, such as a metal, set the
bias to a small value (0.2 V or less). For specimens such as a semiconductor or an
oxide film, set it to a high value (1.0 V or more).
Current/nA
Double-click on the Current/nA, and when the numerical value is highlighted,
g the keyboard; then press the Tab key to finalize the value.
Current/nA is used to specify the tunnel current between the specimen and the tip.
Change it while observing the image that is being scanned. Here, set Current/nA to
Filte
enter 1 usin
1.000 for the time being.
r/Hz
Click on the
button in the Filter/Hz selection box and select 1.0 from the
pull-down menu.
e response speed becomes, thus producing a
tes. Usually, set the highest speed
during
Filter/Hz is the parameter that determines the response speed of the feedback circuit.
The larger the set value is, the faster th
sharp image, but the feedback circuit easily oscilla
at which the feedback circuit does not oscillate while watching an image
scanning.
Loop Gain
Click on the
button in the Loop Gain selection box and select 8 from the
pull-down menu.
The setting determines the gain of the feedback circuit. The larger the set value is,
the higher the response gain becomes, thus obtaining a good image from an uneven
specimen surface, but the feedback circuit easily oscillates.
