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Model 4277A
SECTION III
Parameters of semiconductor devices have a
strong dependency on the applied voltage and
device temperature.
Because of the non-linear
impedance
chanracteristics
of
semiconductor
devices, a semiconductor measurement is subject
to exact establishment of the test conditions to
make
measured
values
meaningful.
For
a
detailed
analysis
of
the
device
under
its
operating test conditions, a low level test signal
is employed in order to obtain measured values
with
respect
to
a
local
region around
the
operating
test
point
selected
for
plotting
characteristic parameter curves of the sample.
A
typical
procedure
for
measuring
semiconductor junction capacitance in P-N and
MOS junction devices is outlined below.
Measurement Setup:
The figure above shows a typical test setup
for
measuring
the
base-collector junction
capacitance (Cob) of an NPN transistor. For
this measurement, the test fixture may be
user designed. A 4277A equipped with option
001
is ideal for
controlling
the dc
bias
required for the measurement. If dc bias is
not
necessary,
setup
and
procedures
associated with this measurement may be
deleted.
PROCEDURE:
1. Connect the test fixture or test cables to the
UNKNOWN terminals of the 4277A.
2. Turn on the 4277A.
3. Set
the
4277A's
front
panel
controls
as
follows:
DISPLAY A: C
DISPLAY B: G
TestFreq.: IMHz
TEST SIG LEVEL: LOW
4. Perform
OPEN
and
SHORT
Zero
Offset
adjustments as described in paragraph 3-51.
5. Set the DC BIAS SELECT switch on the rear
panel to INT.
Note
If an external voltage source is used for
dc biasing, set the DC BIAS SELECT
switch to EXT, and connect the voltage
source output to the EXT INPUT/INT
MONITOR connector on the rear panel.
Note
DC bias voltage, whether supplied from
the internal bias source or from an
external bias source, should be set to
OV at this time.
Note
Use the HP Model 16065A EXTERNAL
VOLTAGE
BIAS
FIXTURE
for
high
voltage bias applications up to ±200V.
6. Connect the transistor to the measurement
terminals.
Figure 3-21. Semiconductor Device Measurement (Sheet 1 of 2).
3-47
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