Structural, electronic, elastic, optical and thermodynamical properties of zinc-blende SiGe, SiSn and GeSn from first principles

Abstract

The structural, electronic, elastic, optical and thermodynamical properties of the ordered SiGe, SiSn and GeSn cubic alloy in zinc-blende (B3) structure are investigated using the plane-wave ultrasoft pseudopotential based on the first principles density functional theory (DFT).The ground state properties such as the lattice parameter, bulk modulus, energy derivative, elastic constants Cij, Young’s modulus, Poisson’s ratio and the Zener anisotropy factor were calculated. The results are in favorable agreement with a previous work. The complex dielectric function, refractive index, extinction coefficient, complex conductivity function, energy loss spectrum, absorption coefficient and optical reflectivity were calculated and the peak position distributions of imaginary parts of the complex dielectric function are explained. The calculated elastic properties are consistent with other calculated results and predicted the Debye temperature, the isochoric heat capacity, the entropy, enthalpy and free energy.

Keywords: density functional theory, elastic properties, optical properties, thermodynamical properties