Tight binding analysis of Si and GaAs ultra thin bodies with subatomic resolution

TL;DR

This paper presents a method to improve empirical tight binding models for ultra-thin silicon and GaAs structures by mapping ab-initio calculations, resulting in more accurate energy bands and wave functions at subatomic resolution.

Contribution

It introduces a new parameterization approach for ETB models based on ab-initio band and wave function mapping, enhancing accuracy for ultra-thin structures.

Findings

ETB models show good agreement with hybrid functional calculations

Localized basis functions improve model precision

Enhanced modeling of ultra-thin device structures

Abstract

Empirical tight binding(ETB) methods are widely used in atomistic device simulations. Traditional ways of generating the ETB parameters rely on direct fitting to bulk experiments or theoretical electronic bands. However, ETB calculations based on existing parameters lead to unphysical results in ultra small structures like the As terminated GaAs ultra thin bodies(UTBs). In this work, it is shown that more reliable parameterizations can be obtained by a process of mapping ab-initio bands and wave functions to tight binding models. This process enables the calibration of not only the ETB energy bands but also the ETB wave functions with corresponding ab-initio calculations. Based on the mapping process, ETB model of Si and GaAs are parameterized with respect to hybrid functional calculations. Highly localized ETB basis functions are obtained. Both the ETB energy bands and wave functions with subatomic resolution of UTBs show good agreement with the corresponding hybrid functional calculations. The ETB methods can then be used to explain realistically extended devices in non-equilibrium that can not be tackled with ab-initio methods.