Band Offsets at Semiconductor-Oxide Interfaces from Hybrid Density Functional Calculations

TL;DR

This paper presents a hybrid density functional approach to accurately calculate band offsets at semiconductor-oxide interfaces by tuning exchange fractions to match experimental band gaps, achieving results that align well with experimental data.

Contribution

The study introduces a novel scheme using hybrid density functionals with tuned exchange fractions to determine band offsets, improving accuracy over previous methods.

Findings

Accurate band offsets for Si-SiO2, SiC-SiO2, and Si-HfO2 interfaces.

The interface level lineup is nearly independent of the exchange fraction.

Excellent agreement with experimental measurements.

Abstract

Band offsets at semiconductor-oxide interfaces are determined through a scheme based on hybrid density functionals, which incorporate a fraction $\alpha$ of Hartree-Fock exchange. For each bulk component, the fraction $\alpha$ is tuned to reproduce the experimental band gap, and the conduction and valence band edges are then located with respect to a reference level. The lineup of the bulk reference levels is determined through an interface calculation, and shown to be almost independent of the fraction $\alpha$. Application of this scheme to the Si-SiO$_2$, SiC-SiO$_2$, and Si-HfO$_2$ interfaces yields excellent agreement with experiment.