Effect of Native Defects on Optical Properties of InxGa1-xN Alloys

TL;DR

This study investigates how high-energy helium ion irradiation modifies the optical absorption edge and carrier populations in InxGa1-xN alloys, revealing defect-induced effects consistent with the amphoteric defect model.

Contribution

It demonstrates the controlled tuning of optical and electronic properties of InxGa1-xN alloys through irradiation-induced native defects, aligning experimental results with defect model predictions.

Findings

Blue shift of absorption edge in In-rich alloys due to band-filling effect.

Introduction of native defects inside the bandgap acting as acceptors in Ga-rich alloys.

Changes in optical properties are consistent with the amphoteric defect model.

Abstract

The energy position of the optical absorption edge and the free carrier populations in InxGa1-xN ternary alloys can be controlled using high energy 4He+ irradiation. The blue shift of the absorption edge after irradiation in In-rich material (x > 0.34) is attributed to the band-filling effect (Burstein-Moss shift) due to the native donors introduced by the irradiation. In Ga-rich material, optical absorption measurements show that the irradiation-introduced native defects are inside the bandgap, where they are incorporated as acceptors. The observed irradiation-produced changes in the optical absorption edge and the carrier populations in InxGa1-xN are in excellent agreement with the predictions of the amphoteric defect model.