Nonequilibrium Green's function theory for predicting device-to-device variability

TL;DR

This paper introduces theoretical formalisms based on nonequilibrium Green's functions to predict device-to-device variability caused by dopant fluctuations in nanoelectronics, enabling efficient analysis without extensive simulations.

Contribution

It develops novel diagrammatic and perturbative formalisms within CPA and LCA for quantum transport variability prediction in doped nanoelectronic devices.

Findings

Formalism applicable to various disorder concentrations

Efficient prediction of transport fluctuations

Validated with tight-binding and first-principles models

Abstract

Due to random dopant fluctuations, the device-to-device variability is a serious challenge to emerging nanoelectronics. In this work we present theoretical formalisms and numerical simulations of quantum transport variability, based on the nonequilibrium Green's functions and the multiple scattering theory. We have developed a general formalism using the diagrammatic technique within the coherent potential approximation (CPA) that can be applied to a wide range of disorder concentrations. In addition, we have developed a method by using a perturbative expansion within the low concentration approximation (LCA) that is extremely useful for typical nanoelectronic devices having low dopant concentration. Applying both formalisms, transport fluctuations due to random impurities can be predicted without lengthy brute force computation of ensemble of devices structures. Numerical implementations of the formalisms are demonstrated using both tight-binding models and first principles models.