Ab initio model of amorphous zinc oxide (a-ZnO) and a-X_0.375 Z_0.625 O (X=Al, Ga and In)

TL;DR

This study uses density functional theory to model the structure and electronic properties of amorphous zinc oxide and its doped variants with Al, Ga, and In, revealing how dopants influence defects and electronic states.

Contribution

It provides the first ab initio models of doped amorphous zinc oxide, analyzing the effects of trivalent dopants on structure and electronic properties.

Findings

Dopants prefer bonding with oxygen atoms.

Dopants introduce coordination defects in the network.

Dopants reduce the electronic density of states gap.

Abstract

Density functional theory (DFT) calculations are carried out to study the structure and electronic structure of amorphous zinc oxide (a-ZnO). The models were prepared by the "melt-quench" method. The models are chemically ordered with some coordination defects. The effect of trivalent dopants in the structure and electronic properties of a-ZnO is investigated. Models of a-X_0.375 Z_0.625 O (X=Al, Ga and In) were also prepared by the "melt- quench" method. The trivalent dopants reduce the four-fold Zn and O, thereby introducing some coordination defects in the network. The dopants prefer to bond with O atom. The network topology is discussed in detail. Dopants reduce the gap in EDOS by producing defect states minimum while maintaining the extended nature of the conduction band edge.