Basic Device Parameters - Keithley 4200A-SCS Reference Manual

Appendix D: Using a Model 82 C-V System

Basic device parameters

The following topics provide additional detail on device parameters and how they are calculated.
Determining device type
The semiconductor conductivity type (p or n dopant ions) can be determined from the relative shape
of the C-V curves (see
indication than the quasistatic curve because of its highly asymmetrical nature. Note that the C-V
curve moves from the accumulation to the inversion region as gate voltage, V
positive for p-type materials, but the curve moves from accumulation to inversion as V
more negative with n-type materials (Nicollian and Brews 372-374).
•
If C is greater when V
H
•
If C is greater with positive V
H
•
The end of the curve where C
the curve is the inversion.
Oxide capacitance, thickness and gate area
The oxide capacitance, C
accumulation. Oxide thickness is calculated from C
Where:
•
t = oxide thickness (nm)
ox
•
A = gate area (cm
•
ε
= permittivity of oxide material (F/cm)
ox
•
C = oxide capacitance (pF)
ox
You can rearrange the above equation to calculate gate area if the oxide thickness is known. Note
that ε
and other constants are initialized for use with silicon substrate, silicondioxide insulator, and
OX
aluminum gate material, but may be changed for other materials.
D-48
Analysis methods (on page D-47)). The high-frequency curve gives a better
is negative than V
GS
than negative V
GS
is greater is the accumulation region, while the opposite end of
H
, is the high-frequency capacitance with the device biased in strong
OX
2
)
Model 4200A-SCS Parameter Analyzer Reference Manual
when poitive, the substrate material is p-type.
GS
, the substrate is n-type.
GS
and gate area as follows:
OX
4200A-901-01 Rev. C / February 2017
, becomes more
GS
becomes
GS