Impact of cation-based localized electronic states on the conduction and valence band structure of AlInN alloys

TL;DR

This study reveals that cation-related localized states significantly influence the band structure of AlInN alloys, causing strong band gap bowing at low indium content, which challenges traditional modeling assumptions.

Contribution

The paper provides first-principles evidence that localized states from indium atoms dominate band structure evolution in AlInN, highlighting the breakdown of constant bowing parameter assumptions.

Findings

Localized states form in both conduction and valence bands at low In content.

Localized states dominate band structure changes with increasing In.

Traditional models assuming constant bowing parameters are inadequate.

Abstract

We demonstrate that cation-related localized states strongly perturb the band structure of $\text{Al}_{1-x}\text{In}_x$N leading to a strong band gap bowing at low In content. Our first-principles calculations show that In-related localized states are formed both in the conduction and the valence band in $\text{Al}_{1-x}\text{In}_x$N for low In composition, $x$, and that these localized states dominate the evolution of the band structure with increasing $x$. Therefore, the commonly used assumption of a single composition-independent bowing parameter breaks down when describing the evolution both of the conduction and of the valence band edge in $\text{Al}_{1-x}\text{In}_x$N.