Analytical modelling of a MOSFET with non-uniform impurity profile

Abstract

A displaced Gaussian profile is used to develop an analytical model for drain current and voltage characteristics of an n‐channel enhancement mode MOSFET. The averaged concentrations over the junction depth of source and drain are also considered as uniform case to compare the results. The threshold voltage in both the cases is calculated for different straggling ranges of the implanted profile. The validity of the averaged assumption for the uniform case and Taylor et. al.'s approximation in the present analysis are checked. The present results reveal that the earlier analyses of a MOSFET with an averaged Gaussian profile upto the junction depth is in error and better insight is achieved by considering a non‐uniform impurity profile. It is also found that Taylor et. al.'s approximation results in more error compared to the averaged case.

Analysis of an MOS inverter with non-uniform impurity profile

“…3. This has been evaluated using our earlier mathematical model of a MOSFET with non-uniform impurity profile [4]. For curve description see caption of Fig.…”

“…1. both transistors are non-uniformly doped, 2. both the transistors are uniformly doped, and 3. one is uniformly doped, the other non-uniformly doped. The steady state transfer characteristics of such type of inverters have been analysed using the basic equation derived in our previous work [4].…”