Stable ordered phases of cuprous iodide with complexes of copper vacancies

TL;DR

This study provides a comprehensive theoretical analysis of Cu-I phases, revealing how Cu vacancy interactions stabilize specific non-stoichiometric structures that influence hole conductivity and electronic properties.

Contribution

It uncovers the role of Cu vacancy interactions in stabilizing non-stoichiometric phases and their impact on electronic properties in Cu-I compounds.

Findings

Cu vacancy interactions stabilize zincblende phases.

Defect complexes influence hole conductivity.

Characteristic DOS peak indicates defect complexes.

Abstract

We perform an exhaustive theoretical study of the phase diagram of Cu-I binaries, focusing on Cu-poor compositions, relevant for p-type transparent conduction. We find that the interaction between neighboring Cu vacancies is the determining factor that stabilizes non-stoichiometric zincblende phases. This interaction leads to defect complexes where Cu vacancies align preferentially along the [100] crystallographic direction. It turns out that these defect complexes have an important influence on hole conductivity, as they lead to dispersive conducting $p$-states that extend up to around 0.8 eV above the Fermi level. We furthermore observe a characteristic peak in the density of electronic states, which could provide an experimental signature for this type of defect complexes.