JEOL JSPM-5200 Instructions Manual page 197

５ MEASUREMENT OPERATION
Bias /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,
enter 1 usin
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
1.000 for the time being.
Filte r/Hz
Click on the
pull-down menu.
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
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.
5-134
This is the pa rameter that determines the scan speed. Naturally, this parameter
should be changed according to the observation area and the unevenness of the
specimen.
g the keyboard; then press the Tab key to finalize the value.
button in the Filter/Hz selection box and select 1.0 from the
button in the Loop Gain selection box and select 8 from the
e response speed becomes, thus producing a
tes. Usually, set the highest speed
during
TMPM5200-2