Ab Initio Investigation of Electronic and Optical Properties of Cu‐Doped As₂S₃

Abstract

The density functional theory with generalized gradient approximation is used to investigate the structural, electronic and optical properties of Cu doped Cu0.125As2S3 and Cu0.25As2S3 configurations with Cu impurity at c‐face centre interstitial site. The As‐S bond lengths remain nearly the same but Cu‐S bond lengths decrease with increase in Cu concentration. Both the configurations are n‐type semiconductors which agree with the experimental observations. The density of Cu d states in the valence band increases with increase in Cu content. There is strong p‐d hybridization in valence and conduction bands in both the configurations. The calculated optical constants are strongly anisotropic upto 10 eV, however at higher energies the anisotropy diminishes. The broad peaks in the optical constants along || and axes are found in the vicinity of 2 eV. However, the peak heights increase and shift towards lower energy with increase in Cu content. Further static dielectric constant, refractive index and reflectivity increase and the optical band gap decreases with increase in Cu concentration. The calculated optical band gap is more close to the experimental value for Cu0.25As2S3 configuration. The comparison of optical constants shows that Cu0.25As2S3 may be as good choice as Ag0.25As2S3 for optical applications.This article is protected by copyright. All rights reserved.