Investigation of thermodynamic and mechanical properties of AlyIn1−yP alloys by statistical moment method

The thermodynamic and mechanical properties of III-V zinc-blende AlP, InP semiconductors and their alloys have been studied in detail from statistical moment method taking into account the anharmonicity effects of the lattice vibrations. The nearest neighbor distance, thermal expansion coefficient, bulk moduli, specific heats at the constant volume and constant pressure of the zincblende AlP, InP and Al_yIn_1−yP alloys are calculated as functions of the temperature. The statistical moment method calculations are performed by using the many-body Stillinger-Weber potential. The concentration dependences of the thermodynamic quantities of zinc-blende Al_yIn_1−yP crystals have also been discussed and compared with those of the experimental results. Our results are reasonable agreement with earlier density functional theory calculations and can provide useful qualitative information for future experiments. The moment method then can be developed extensively for studying the atomistic structure and thermodynamic properties of nanoscale materials as well.