Appendix D: Using a Model 82 C-V System
Model 4200A-SCS Parameter Analyzer Reference Manual
D-24
4200A-901-01 Rev. C / February 2017
Choosing the right parameters
This section describes how to choose the correct parameters for:
•
Simultaneous C-V measurement
•
The delay time to ensure that the device remains in equilibrium in the inversion region during a
sweep
•
Controlling errors at the source
Optimal C-V measurement parameters
Simultaneous C-V measurement is a complicated matter. Besides system considerations, you should
carefully choose the measurement parameters. Refer to the following discussion for considerations
when selecting these parameters.
Start, stop, and step voltages
Most C-V data is derived from the sweep transition, or depletion region of the C-V curve. For that
reason, start and stop voltages should be chosen so that the depletion region makes up about 1/3 to
2/3 of the voltage range.
Figure 600: Typical simultaneous C-V curve
The upper flat, or accumulation region of the high frequency C-V curve defines the oxide capacitance,
COX. Since most analysis relies on the ratio C/COX, it is important that you choose a start or stop
voltage (depending on the sweep direction) to bias the device into strong accumulation at the start or
the end of the sweep.
You should carefully consider the size of the step voltage. Start, stop, and step size determine the
total number of data points in the sweep. Some compromise is necessary between having too few
data points in one situation, or too many data points in the other.
