Keithley 4200A-SCS Reference Manual page 1192

Model 4200A-SCS Parameter Analyzer Reference Manual
Threshold voltage
The threshold voltage, V
the bulk potential, φ
enhancement mode MOSFET, V
V is calculated as follows:
TH
Where:
•
V = threshold voltage (V)
TH
•
A = gate area (cm
•
C
OX
•
12
10
•
ε
= permittivity of substrate material
S
•
q = electron charge (1.60219 × 10
•
N
BULK
•
φ
= bulk potential (V)
B
•
V = flatband voltage (V)
FB
Metal semiconductor work function difference
The metal semiconductor work function difference, W
It contributes to the shift in V
(Nicollian and Brews 462-477; Sze 395402). The work function represents the difference in work
necessary to remove an electron from the gate and from the substrate, and it is derived as follows:
Where:
•
W = metal work function (V)
M
•
W = substrate material work function (electron affinity) (V)
S
•
E = substrate material bandgap (V)
G
•
φ
= bulk potential (V)
B
4200A-901-01 Rev. C / February 2017
, is the point on the C-V curve where the surface potential ψ
TH
. This point on the curve corresponds to the onset of strong inversion. For an
B
TH
2
)
= oxide capacitance (pF)
= units multiplier
-3
= bulk doping (cm )
from the ideal zero value, along with the effective oxide charge
FB
corresponds to the point where the device begins to conduct.
-19
coulombs)
, is commonly referred to as the work function.
MS
Appendix D: Using a Model 82 C-V System
, equals twice
S
D-51