Analytical model of nanowire FETs in a partially ballistic or dissipative transport regime

TL;DR

This paper introduces a simple analytical model that describes the intermediate transport regimes in nanoscale FETs, bridging ballistic and dissipative behaviors, with application to silicon nanowire transistors.

Contribution

It proposes a unified analytical model for quasi-one-dimensional FETs covering all transport regimes, linking mobility and mean free path.

Findings

Model seamlessly covers ballistic to dissipative regimes

Relation between mobility and mean free path established

Application demonstrated on silicon nanowire transistors

Abstract

The intermediate transport regime in nanoscale transistors between the fully ballistic case and the quasi equilibrium case described by the drift-diffusion model is still an open modeling issue. Analytical approaches to the problem have been proposed, based on the introduction of a backscattering coefficient, or numerical approaches consisting in the MonteCarlo solution of the Boltzmann transport equation or in the introduction of dissipation in quantum transport descriptions. In this paper we propose a very simple analytical model to seamlessly cover the whole range of transport regimes in generic quasi-one dimensional field-effect transistors, and apply it to silicon nanowire transistors. The model is based on describing a generic transistor as a chain of ballistic nanowire transistors in series, or as the series of a ballistic transistor and a drift-diffusion transistor operating in the triode region. As an additional result, we find a relation between the mobility and the mean free path, that has deep consequences on the understanding of transport in nanoscale devices.