Calculation of DOS-Dependent Channel Potentials in FETs in the Saturation Condition

TL;DR

This study models the channel potential in FETs considering various DOS levels, revealing a universal analytical fit and a correction factor for charge density in saturation conditions.

Contribution

It introduces an analytical function for the channel potential in FETs with different DOS, enhancing understanding of charge behavior in saturation.

Findings

Vch fits an analytical function with a power k dependent on DOS

The power k varies from 0 to 0.5 across DOS levels

A correction factor alpha between 0.65 and 1.0 accurately describes charge density

Abstract

We calculated functions for the potential, Vch, in the channel of a field effect transistor with various densities of the localized states (DOS) by using a device simulator. In the saturation condition, Vch is found to fit satisfactorily to the analytical function, Vch(y)=Vg(1-(1-y/L) k), where Vg is the gate bias, y is the position along the channel, and L is the channel length. The power k, which depends on the DOS, ranges from 0 to 0.5 even with an extensive variation of DOS. As a result, the total induced charge density in the saturation condition can be expressed a way similar to the linear condition by introducing a correction factor, alpha, ranging between 0.65 and 1.0.