First-principle calculations of structural and optoelectronic properties of cubic CdxZn1−xSySe1−y quaternary alloys with modified Becke–Johnson (mBJ) functional

Abstract

First-principle calculations in association with modified Becke–Johnson (mBJ-GGA) potentials have been performed on optoelectronic properties of CdxZn1−xSySe1−y quaternary alloys. Each semiconductor specimen within this quaternary system is a direct band gap (Γ–Γ) semiconductor. An increase in anionic (S) concentration y results in nonlinear decrease in lattice constant and increase in bulk modulus and fundamental band gap (Eg) at each cationic (Cd) concentration x. In contrast, reverse trend is observed in cationic concentration (x) dependence of each of these parameters at each anionic concentration (y). Calculated lattice constant and band gap versus concentrations (x, y) contour plots are useful in designing new quaternary alloys with targeted optoelectronic properties. An increase in calculated Eg results in decrease in each of the calculated static dielectric constant $$ \varepsilon_{1} (0) $$ , static refractive index n(0), static reflectivity R(0) and vice versa. On the other hand, an increase in calculated Eg results in the enhancement in calculated critical point energy (Ec) in each of the imaginary dielectric function $$ \varepsilon_{2} (\omega ) $$ , extinction coefficient $$ k(\omega ) $$ , optical conductivity $$ \sigma (\omega ) $$ , absorption $$ \alpha (\omega ) $$ spectra and vice versa. Calculations have also shown that zinc blende GaAs and ZnSe are suitable substrates for the growth of several CdxZn1−xSySe1−y quaternary alloys.