# Ab initio calculations of the concentration dependent band gap reduction in dilute nitrides

## TL;DR

This study demonstrates that combining advanced density functional theory with careful supercell design enables accurate ab initio predictions of band gap reduction in dilute nitrides, overcoming previous computational challenges.

## Contribution

It introduces a methodology that allows for reliable ab initio calculations of dilute nitride semiconductors by addressing supercell size and distortion effects.

## Key findings

- Accurate band gap predictions matching experimental data.
- Supercell size must prevent overlap of N atom distortion fields.
- Method enables predictive modeling of dilute nitride electronic properties.

## Abstract

While being of persistent interest for the integration of lattice-matched laser devices with silicon circuits, the electronic structure of dilute nitride III/V-semiconductors has presented a challenge to ab initio computational approaches. The root of this lies in the strong distortion N atoms exert on most host materials. Here, we resolve these issues by combining density functional theory calculations based on the meta-GGA functional presented by Tran and Blaha (TB09) with a supercell approach for the dilute nitride Ga(NAs). Exploring the requirements posed to supercells, we show that the distortion field of a single N atom must be allowed to decrease so far, that it does not overlap with its periodic images. This also prevents spurious electronic interactions between translational symmetric atoms, allowing to compute band gaps in very good agreement with experimentally derived reference values. These results open up the field of dilute nitride compound semiconductors to predictive ab initio calculations.