Influence of surface potential fluctuations on the operation of a MOS transistor in weak inversion

The existing theories describing the MOS transistor operation in weak inversion do not take into account the influence of surface potential fluctuations, caused by oxide charge fluctuations. These theories explain the difference between the theoretical and experimental slope of the log
e
I
D
-V
G
curves by the capture of minority carriers by surface states. The density of surface states necessary to explain this difference lies between
5 \times 10^{10}
and
2 \times 10^{11}
cm
^-2
V
^-1
.