Inflection Phenomenon in Cryogenic MOSFET Behavior

TL;DR

This paper presents an analytical model and measurements of the inflection phenomenon in cryogenic MOSFET transfer characteristics, attributing it to localized states and enabling extraction of their density from current data.

Contribution

The study introduces a novel analytical model explaining the inflection in cryogenic MOSFETs and links it to localized states, providing a method to quantify interface trap density.

Findings

Inflection causes inward bending of the drain current at cryogenic temperatures.

Localized states centered around the band edge explain the inflection phenomenon.

The model enables extraction of localized state density from dc measurements.

Abstract

This brief reports the analytical modeling and measurements of the inflection in the MOSFET transfer characteristics at cryogenic temperatures. Inflection is the inward bending of the drain current versus gate voltage, which reduces the current in weak and moderate inversion at a given gate voltage compared to the drift-diffusion current. This phenomenon is explained by introducing a Gaussian distribution of localized states centered around the band edge. The localized states are attributed to disorder and interface traps. The proposed model allows to extract the density of localized states at the interface from the dc current measurements.