Band structure calculations of CuAlO2, CuGaO2, CuInO2 and CuCrO2 by screened exchange

TL;DR

This study uses hybrid functional DFT calculations to accurately determine the electronic band structures and optical properties of several copper-based transparent conducting oxides, improving upon previous methods.

Contribution

The paper demonstrates that hybrid functional sX-LDA provides significantly better electronic property predictions for Cu-based oxides than standard DFT approaches.

Findings

Band gaps align well with experimental data.

Improved predictions of Cu d and O p level energies.

Calculated dielectric functions offer insights into optical properties.

Abstract

We report density functional theory (DFT) band structure calculations on the transparent conducting oxides CuAlO2, CuGaO2, CuInO2 and CuCrO2. The use of the hybrid functional sX-LDA leads to considerably improved electronic properties compared to standard local density approximation (LDA) and generalized gradient approximation (GGA) approaches. We show that the resulting electronic band gaps compare well with experimental values and previous quasiparticle calculations and show the correct trends with respect to the atomic number of the cation (Al, Ga, In). The resulting energetic depths of Cu d and O p levels and the valence band widths are considerable improvements compared to LDA and GGA and in good agreement with available x-ray photoelectron spectroscopy (XPS) data. Lastly, we show the calculated imaginary part of the dielectric function for all four systems.