Anomalous band-gap bowing of AlN(1-x)Px alloy

TL;DR

This study investigates the electronic structure and band-gap behavior of AlN(1-x)Px alloy using first-principles calculations, revealing anomalous bowing effects influenced by structural modeling approaches and atomic arrangements.

Contribution

It compares VCA and supercell methods for calculating band-gaps and structural parameters, highlighting the impact of atomic configuration on band-gap bowing in AlN(1-x)Px.

Findings

VCA shows anomalous lattice constant bowing.

Supercell calculations reveal configuration-dependent band-gap bowing.

Clustered atom arrangements cause significant band-gap anomalies.

Abstract

Electronic structure of zinc blende AlN(1-x)$Px alloy has been calculated from first principles. Structural optimisation has been performed within the framework of LDA and the band-gaps calculated with the modified Becke-Jonson (MBJLDA) method. Two approaches have been examined: the virtual crystal approximation (VCA) and the supercell-based calculations (SC). The composition dependence of the lattice parameter obtained from the SC obeys Vegard's law whereas the volume optimisation in the VCA leads to an anomalous bowing of the lattice constant. A strong correlation between the band-gaps and the structural parameter in the VCA method has been observed. On the other hand, in the SC method the supercell size and atoms arrangement (clustered vs. uniform) appear to have a great influence on the computed band-gaps. In particular, an anomalously big band-gap bowing has been found in the case of a clustered configuration with relaxed geometry. Based on the performed tests and obtained results some general features of MBJLDA are discussed and its performance for similar systems predicted.