Electronic and phononic properties of the chalcopyrite CuGaS2

TL;DR

This study combines theoretical and experimental approaches to analyze the electronic, vibrational, and thermodynamic properties of the chalcopyrite semiconductor CuGaS2, highlighting isotope effects and validating computational models against experimental data.

Contribution

It provides comprehensive vibronic and thermodynamic data for CuGaS2, including phonon dispersion and isotope effects, using ab initio calculations and experimental validation.

Findings

Calculated phonon dispersion relations match experimental data.

Isotope substitution significantly affects thermodynamic properties.

Theoretical models accurately predict lattice parameters and specific heat.

Abstract

The availability of ab initio electronic calculations and the concomitant techniques for deriving the corresponding lattice dynamics have been profusely used for calculating thermodynamic and vibrational properties of semiconductors, as well as their dependence on isotopic masses. The latter have been compared with experimental data for elemental and binary semiconductors with different isotopic compositions. Here we present theoretical and experimental data for several vibronic and thermodynamic properties of CuGa2, a canonical ternary semiconductor of the chalcopyrite family. Among these properties are the lattice parameters, the phonon dispersion relations and densities of states (projected on the Cu, Ga, and S constituents), the specific heat and the volume thermal expansion coefficient. The calculations were performed with the ABINIT and VASP codes within the LDA approximation for exchange and correlation and the results are compared with data obtained on samples with the natural isotope composition for Cu, Ga and S, as well as for isotope enriched samples.