Theoretical study on the origins of the gap bowing in CaxMg1-xS alloys

The structural, electronic properties of three chalcogenide compounds MgS ,CaS and their CaxMg1-xS ternary alloy in the rockslat phase have been investigated by using the full-potential linearized augmented plane-wave method... [ view full abstract ]

The structural, electronic properties of three chalcogenide compounds MgS ,CaS and their Ca_xMg_1-xS ternary alloy in the rockslat phase have been investigated by using the full-potential linearized augmented plane-wave method (FP-LAPW) within density functional theory (DFT). We employed the local density approximation (LDA) and generalized gradient approximation (GGA) for the calculation of exchange-correlation (XC) potential. The equilibrium lattice constants and the bulk modulus are in agreement with the values reported in the literature, their deviation from linearity has been examined and discussed. From the study of the electronic properties, we find that these binary compounds MgS and CaS, have indirect band gaps.

For ternary alloy Ca_xMg_1-xS the study of these various properties are calculated, particularly the variation of structural and electronic parameters with concentration x. We focused our attention on the origins of bowing parameters corresponding to these physical properties.

In this study, we compare these predictions to the results already obtained experimentally as well as theoretical work in this regard.