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.
@article{arxiv.2009.06273,
title = {Stable ordered phases of cuprous iodide with complexes of copper vacancies},
author = {Stefan Jaschik and Mário R. G. Marques and Michael Seifert and Claudia Rödl and Silvana Botti and Miguel A. L. Marques},
journal= {arXiv preprint arXiv:2009.06273},
year = {2020}
}