4: Multi-frequency capacitance-voltage unit Model 4200A-SCS Parameter Analyzer
4-80 4200A-901-01 Rev. C / February 2017
MOSFET Project (mosfet)
This project contains DC I-V, C-V, and pulse I-V tests for a MOSFET. It makes C-V measurements to
explore the basic operation and parameters of the device. Since the high-frequency operation and
switching speed of a MOSFET are dependent on the capacitance of the device, capacitance
measurements are often made to various parts of the device. For example, the capacitance between
the gate and channel (C
GD
and C
GS
) is important because it creates the charges necessary for
operating the devices. This gate-channel capacitance depends on the applied voltage and the
operating region.
Capacitance measurements are made to various parts of the device, as shown in the following figure.
Figure 133: N-MOSFET with terminal capacitances
C-V measurements are often made on MOSFETs to extract particular device parameters, such as
oxide capacitance (C
OX
), flatband capacitance (C
FB
), and oxide thickness (T
OX
).
The g-to-sdb test generates a capacitance versus voltage graph. It plots the capacitance as a
function of the gate voltage from the two-terminal measurement. A typical two-terminal C-V curve of
an N-channel MOSFET is shown in the next figure.
Figure 134: N-channel MOSFET g-to-sdb graph
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