Anomalous composition dependence of the band gap pressure coefficients in In-containing nitride semiconductors

Abstract

The pressure-induced changes in the electronic band structures of In-containing nitride alloys, ${\text{In}}_{x}{\text{Ga}}_{1\text{\ensuremath{-}}x}\text{N}$ and ${\text{In}}_{x}{\text{Al}}_{1\text{\ensuremath{-}}x}\text{N}$ are examined experimentally as well as by ab initio calculations. It is found that the band gap pressure coefficients, $d{E}_{g}/dp$, exhibit very large bowing with $x$, and calculations with simulation of clustered distributions of the In atoms over the cation sites show a strong enhancement of this effect. This relates well to the experimental data obtained from pressure dependent photoluminescence measurements for ${\text{In}}_{x}{\text{Ga}}_{1\text{\ensuremath{-}}x}\text{N}$ and ${\text{In}}_{x}{\text{Al}}_{1\text{\ensuremath{-}}x}\text{N}$ layers, performed in this work, and combined with existing data for ${\text{In}}_{x}{\text{Ga}}_{1\text{\ensuremath{-}}x}\text{N}$ layers. We discuss possible explanations of the anomalously large magnitude of the $d{E}_{g}/dp$ bowing in these nitride alloys.