Electronic structure calculations on copper substituted silver iodide through modified Becke-Johnson exchange potential

Abstract

Silver iodide (AgI) has a rich phase diagram with the γ-AgI being one of the forms. γ-AgI is a n-type semiconductor that crystallizes into zinc blende structure and found to be stable at ambient temperature and pressure. The electrical transport in γ-AgI is mediated by the migration of Ag+ cationic interstitial defects, while the Cu + Frenkel defects are responsible for the conduction in γ-CuI, a p-type semiconductor. This intrigues to understand the transition of the nature of electrical transport with the replacement of Ag by Cu. In this regard, we report the computational study on the Cu substituted γ-AgI using the density functional theory (DFT) with Tran-Blaha modified Becke-Johnson (TB-mBJ) scheme. The calculations are performed on γ-Ag1-xCuxI (x = 0.00–1.00) supercell through full potential linearized augmented plane wave (FP-LAPW) method. The lattice parameter and bulk modulus are found to vary nearly linear with copper concentration x, whereas band gap values follow a non-linear variation.