Revised theoretical limit of subthreshold swing in field-effect transistors

TL;DR

This paper establishes a new temperature-independent limit for subthreshold swing in MOSFETs at cryogenic temperatures, linked to lattice properties and band tail effects, challenging the traditional Boltzmann limit.

Contribution

It introduces a revised theoretical limit for subthreshold swing in MOSFETs at deep-cryogenic temperatures, considering band tail effects and lattice periodicity.

Findings

Subthreshold swing saturates below a critical temperature.

Saturation value is independent of temperature.

Band tail effects are linked to lattice properties.

Abstract

This letter reports a temperature-dependent limit for the subthreshold swing in MOSFETs that deviates from the Boltzmann limit at deep-cryogenic temperatures. Below a critical temperature, the derived limit saturates to a value that is independent of temperature and proportional to the extent of a band tail. Since the saturation is universally observed in different types of MOSFETs (regardless of dimension or semiconductor material), the band tail is attributed to the finite periodicity of the lattice in a semiconductor volume, and to a lesser extent to additional lattice perturbations such as defects or disorder.