Structural and electronic properties of Zn1−xMgxSySe1−y alloys

The structural and electronic properties of Zn1−xMgxSySe1−y quaternary alloys have been investigated using the full potential-linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). We used the generalized gradient approximation (GGA) that is based on exchange-correlation energy optimization for calculating the total energy. Moreover, the Engel-Vosko GGA formalism is applied so as to optimize the corresponding potential for band-gap structure calculations. We investigated the effect of composition on lattice constant, bulk modulus and band gap. A non-linear dependence on the compositions x and y is observed for all the three properties. The energy gap Eg(x, y) has been determined over the entire compositions x and y. In addition, the energy gap of zinc-blende Zn1−xMgxSySe1−y quaternary alloys in conditions of lattice matched to GaAs substrate has been investigated.