Fundamental properties of zinc-blende AlSb, BSb and their Al1-xBxSb ternary alloys

The structural and electronic properties of the AlSb and BSb compounds and of the Al1-xBxSb ternary alloys are investigated using the full potential-linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). The lattice constant of the Al1-xBxSb alloys exhibits a marginal deviation from Vegard's law and a small deviation of the bulk modulus from linear concentration dependence (LCD) is found. The composition dependence of the energy band gap is non-linear. The approach of Zunge and co-workers is used to explain the microscopic origins of the gap bowing. In order to investigate the thermodynamic stability of the alloys, the excess enthalpy of mixing ΔHm is calculated as a function of the concentration x and the phase diagram is deduced. The quasi-harmonic Debye model is applied to determine the thermal properties of the alloys up to 500 K.