Bandgaps and band bowing in semiconductor alloys

TL;DR

This paper introduces a rapid and realistic dielectric scaling method based on a scissor approximation for calculating bandgaps and band bowing in semiconductor alloys, accounting for dielectric constant variations.

Contribution

The method provides a fast way to compute dielectric constants and band bowing parameters in semiconductor alloys, improving accuracy for highly mismatched alloys.

Findings

The approach yields band bowing parameters that differ from LDA calculations.

It accurately captures the bowing behavior in highly mismatched alloys.

The dielectric scaling method is computationally efficient.

Abstract

The bandgap and band bowing parameter of semiconductor alloys are calculated with a fast and realistic approach. The method is a dielectric scaling approximation that is based on a scissor approximation. It adds an energy shift to the bandgap provided by the local density approximation (LDA) of the density functional theory (DFT). The energy shift consists of a material-independent constant weighted by the inverse of the high-frequency dielectric constant. The salient feature of the approach is the fast calculation of the dielectric constant of alloys via the Green function (GF) of the TB-LMTO (tight-binding linear muffin-tin orbitals) in the atomic sphere approximation (ASA). When it is applied to highly mismatched semiconductor alloys (HMAs) like Zn Te$_x$ Se$_{1-x}$, this method provides a band bowing parameter that is different from the band bowing parameter calculated with the LDA due to the bowing exhibited also by the high-frequency dielectric constant.