Structural, electronic and optical properties of AgXY2(X = Al, Ga, In and Y = S, Se, Te)

The structural, electronic and optical properties of the ternary semiconducting compounds AgXY2 (X = Al, Ga, In and Y = S, Se, Te) in Heusler and chalcopyrite crystal phases have been investigated using the density functional theory (DFT) based on the full potential linear augmented plane wave (FP-LAPW) method. The calculated lattice constant and band gap values for AgXY2 in chalcopyrite phase are in good agreement with the available experimental data. Band structure calculations are performed using modified Becke-Johnson (mBJ) method which match closely with experimental data and yield better band gaps rather than those obtained by using generalized gradient approximation (GGA) and Engel-Vosko generalized gradient approximation (EV-GGA). Decrease in band gap is observed by changing cations X and Y from the top to bottom of periodic table. Chemical bonding trends are predicted through charge density plots and quantified by Bader's analysis. Optical properties reveal that these compounds are suitable candidates for optoelectronic devices in the visible and ultraviolet (UV) regions. (C) 2014 Elsevier B.V. All rights reserved.