The properties of amorphous GaN

TL;DR

This study uses first principles simulations to analyze the structure, electronic properties, and vibrational characteristics of amorphous GaN, revealing insights into its optical gap, tail states, and potential doping behaviors.

Contribution

It introduces three amorphous GaN models from first principles and provides detailed analysis of their structural, electronic, and vibrational properties, including the nature of tail states.

Findings

Predicted optical gap of 3.0 eV for 64-atom model

Predicted optical gap of 2.3 eV for 250-atom models

Identified localized valence tail and delocalized conduction tail

Abstract

In this paper, we present three amorphous GaN models obtained from the first principles simulation. We find that a chemically ordered continuous random network is the ideal structure for a-GaN. If we exclude the tail states, we predict a 3.0eV optical gap for 64-atom model and 2.3eV for 250-atom models. We observe a highly localized valence tail and a remarkably delocalized exponential conduction tail which we associate with different hybridization in the two tails. Based upon these results, we speculate on potential differences in n and p type doping. The structural origin of tail and defect states is discussed. The vibrational density of states and dielectric function are computed, and are consistent with experiment.