Using the Boonton automatic capacitance bridge
This instrument is used to measure CV characteristics.
I. Check wiring
A. Toggle probe station connection switch from IV to CV
B. Make sure that the test wires from the Boonton Capacitance Bridge are in
line with the contact probes connections you wish to use.
C. The DC voltage only works in the positive direction (HI with respect to LOW).
It may be necessary to reverse the probe connections on the wiring box to get
the right direction.
II. Zeroing
A. Lift the contact probe off the sample to zero the instrument.
B. Switch the PANEL MODE to MEASURE position and set TRIGGER to CONTINUOUS
C. CAPACITANCE MODE to Cp (parallel capacitor model, Cs is in series)
D. CAPACITANCE RANGE pF to 2 (you may have to go higher depending on device
size)
E. CONDUCTANCE RANGE uS to 2 (again, can be changed)
F. LOSS MODE to G
G. Adjust zero C fine control to obtain zero +/-100 count indication on left
readout, adjust G fine count to +/-10 count on right readout.
H. If fine control is out of range adjust the course adjust using a jeweler's
screwdriver.
III. Check contacts
A. Use the back contact and one of the probe contacts for your devices.
B. Refer to the IV characterization procedure and check to make sure a good
contact is made by looking at the IV trace. (This will involve setting the switching
box to IV again).
C. It may be necessary to turn off microscope TV monitor to reduce interference.
D. Once this is done, on the curver tracer turn down the variable collector
supply and set left/off/right switch to off.
IV. Programming the instrument
A. Set TEST LEVEL mV control to 50mV or to the highest level permissible for
the test specimen.
B. Set PANEL MODE switch to ENTER position
C. Press ENTER-CLEAR switch
D. Program the desired voltage using SET BIAS (V) or C STD switches (from 0-9,
Dec Pt), start with 0, and press ENTER-BIAS. (Note, in enter mode the lower
red indicators tell what each button means).
E. If an error is made or if you want to change the bias, press ENTER-CLEAR
and reenter SET BIAS, and press ENTER-BIAS.
F. Bias up to 200 V can be programmed, but you may destroy your device if this
is too high.
G. Toggle the PANEL MODE switch back to Measure.
H. Read the capacitance in pF in the left readout, right panel readout can be
changed to measure uS, kOhm, etc.
I. Change the desired readout scale if necessary or set to AUTO for autoscale.
J. Repeat the procedure at different voltages, and record your findings.
K. Check and make sure that your voltage leads are going in the correct direction,
it may be necessary to switch the contact probes especially if you want both
plus and minus readings
V. Shutdown procedure
A. Set bias voltage to zero
B. Turn off the Boonton
C. Flip probe station switch to off position
D. Turn off microscope monitor AND ILLUMINATOR
E. Shut down procedure for the IV tracer (turn down voltage, flip left/off/right
to off, main power off)
F. Turn off brain.