Theory of the electronic structure of dilute bismide and bismide-nitride alloys of GaAs: Tight-binding and k.p models

TL;DR

This paper develops tight-binding and k.p models to analyze the electronic structure of dilute bismide and bismide-nitride GaAs alloys, revealing their potential for tunable optoelectronic applications.

Contribution

It introduces new theoretical models for GaBiAs and GaBiNAs alloys, accurately matching experimental data and enabling better understanding of their electronic properties.

Findings

Band gap energy decreases with Bi addition.

Spin-orbit-splitting energy increases significantly.

Models agree well with experimental observations.

Abstract

The addition of dilute concentrations of bismuth (Bi) into GaAs to form GaBiAs alloys results in a large reduction of the band gap energy Eg accompanied by a significant increase of the spin-orbit-splitting energy (delta_SO), leading to an Eg < delta_SO regime for ~10% Bi composition which is technologically relevant for the design of highly efficient photonic devices. The quaternary alloy GaBiNAs offers further flexibility for band gap tuning, because both nitrogen and bismuth can independently induce band gap reduction. This work reports sp3s* tight binding and 14-band k.p models for the study of the electronic structure of GaBiAs and GaBiNAs alloys. Our results are in good agreement with the available experimental data.