Electronic and valleytronic properties of crystalline boron-arsenide tuned by strain and disorder

TL;DR

This study uses advanced computational methods to explore how strain and disorder affect the electronic and valleytronic properties of cubic boron arsenide, revealing potential for optoelectronic and valleytronic applications.

Contribution

It demonstrates how strain and disorder modify BAs's electronic structure, enabling valleytronics and p-type conductivity, with implications for semiconductor device engineering.

Findings

Strain and disorder reduce the band gap of BAs.

A V-shaped p-band state emerges under strain and disorder.

Biaxial tensile strain makes BAs resemble GaAs in valence band structure.

Abstract

Ab initio density functional theory (DFT) and DFT plus coherent potential approximation (DFT+CPA) are employed to reveal, respectively, the effect of in-plane strain and site-diagonal disorder on the electronic structure of cubic boron arsenide (BAs). It is demonstrated that tensile strain and static diagonal disorder both reduce the semiconducting one-particle band gap of BAs, and a V-shaped p-band electronic state emerges -- enabling advanced valleytronics based on strained and disordered semiconducting bulk crystals. At biaxial tensile strains close to 15% the valence band lineshape relevant for optoelectronics is shown to coincide with one reported for GaAs at low energies. The role played by static disorder on the As sites is to promote p-type conductivity in the unstrained BAs bulk crystal, consistent with experimental observations. These findings illuminate the intricate and interdependent changes in crystal structure and lattice disorder on the electronic degrees of freedom of semiconductors and semimetals.