Electronic structure and optical properties of ZnX (X=O, S, Se, Te)

TL;DR

This study investigates the electronic and optical properties of zinc monochalcogenides with different structures using ab initio methods, providing insights into their spectra, band gaps, and comparison with experimental data.

Contribution

It applies various density functional approaches to calculate optical spectra and estimates the band gap of ZnO in zinc-blende structure, enhancing understanding of these materials.

Findings

Optical spectra can be approximated by a rigid shift to match experiments.

Calculated and experimental band gaps show good agreement.

Estimated band gap of ZnO with zinc-blende structure.

Abstract

Electronic band structure and optical properties of zinc monochalcogenides with zinc-blende- and wurtzite-type structures were studied using the ab initio density functional method within the LDA, GGA, and LDA+U approaches. Calculations of the optical spectra have been performed for the energy range 0-20 eV, with and without including spin-orbit coupling. Reflectivity, absorption and extinction coefficients, and refractive index have been computed from the imaginary part of the dielectric function using the Kramers--Kronig transformations. A rigid shift of the calculated optical spectra is found to provide a good first approximation to reproduce experimental observations for almost all the zinc monochalcogenide phases considered. By inspection of the calculated and experimentally determined band-gap values for the zinc monochalcogenide series, the band gap of ZnO with zinc-blende structure has been estimated.