Topology of amorphous tetrahedral semiconductors on intermediate lengthscales

TL;DR

This paper introduces a new structural model for amorphous tetrahedral semiconductors like a-GaAs, revealing their intermediate-range topology and demonstrating the model's advantages over traditional simulation methods.

Contribution

The study develops a novel, less computationally intensive structural model for amorphous tetrahedral semiconductors that accurately captures intermediate-range topology and reduces wrong bonds.

Findings

Model for a-GaAs has fewer wrong bonds and better coordination.

Traditional models are less accurate and more computationally demanding.

Provides first direct insights into intermediate-range topology in amorphous tetrahedral semiconductors.

Abstract

Using the recently-proposed ``activation-relaxation technique'' for optimizing complex structures, we develop a structural model appropriate to a-GaAs which is almost free of odd-membered rings, i.e., wrong bonds, and possesses an almost perfect coordination of four. The model is found to be superior to structures obtained from much more computer-intensive tight-binding or quantum molecular-dynamics simulations. For the elemental system a-Si, where wrong bonds do not exist, the cost in elastic energy for removing odd-membered rings is such that the traditional continuous-random network is appropriate. Our study thus provides, for the first time, direct information on the nature of intermediate-range topology in amorphous tetrahedral semiconductors.