Selenium alloying of indium sulfide: Ab-initio study of structural, electronic and optical features

In the framework of density functional calculations and using the Linear Augmented Plane Waves with local orbital method (LAPW+lo), we have investigated the structural, electronic and optical properties of indium sulfoselenide (InS1−xSex). The present study confirms that InS1−xSex are indirect band gap materials. The non-linear dependence concentration x of the theoretical forbidden energy band is clearly visible and the microscopic origins of gap bowing are identified and calculated. In order to identify the angular momentum characteristics of the bands structure, the total and partial densities of states (DOS and PDOS) are analyzed. The feature bonding is also investigated from charge density study. Using the projected total densities of states (DOS) and the bands structure, we have calculated the linear optical properties, namely, the complex dielectric function ε(ω), refractive index n(ω), absorption coefficient α(ω) and the electron energy loss L(ω). In particular, we take into account the effect of Se composition on anisotropy, real part of the dielectric function and refractive index. The present alloy is found to be a challenging material in optoelectronic, medical and photovoltaic devices. Good agreements are found with the available experimental and theoretical results.