First-Principles Calculations Of Thermodynamic Properties For Arsenide Semiconductor

The Ⅲ-Ⅴ group compounds XAs (X=Al, Ga and In) have been drawn profound attention due to their applications in fabricating hetero-structures and tunable devices in the visible wavelength region, optoelectronic devices, explicitly for high frequency, because of excellent thermodynamic properties and mechanical properties. Aluminum arsenide (AlAs) is one of the promising XAs semiconductors. It is the important electronic and photoelectric material, which plays an important role in making heterostructure and superstructures. In this paper, the thermodynamic and lattice dynamic properties of XAs (X=A1, Ga and In) were systematically studied by using first-principles calculations.Firstly, the first-principles calculations were adopted to investigate the electronic density of states, band structure, dielectric and vibrational properties of XAs alloys. The imaginary part of dielectric curves ε2(ω) was also determined from the calculated band structure. The results show that the main peak is related to the transition energy Γ15x-15v, proved the indirect band gap semiconductor of AlAs, while GaAs and InAs are classified into direct band gap semiconductors due to their main peaks are related to the transition energyZ,X1c-X5v.Secondly, the phase transformation pressure and transition path from B3to B8phase in AlAs was studied. The effect of pressure on band structures, elastic constants, dielectric functional curves, Phonon-dispersion curves were discussed in this paper. We found that the elastic constants, Bulk modulus, static dielectric constants and the optical phonon frequencies of B3structure and elastic constants of B8structure have varied in a nearly linear behavior with application of hydrostatic pressure.Finally, the first-principles calculations were adopted to study the electronic properties of intrinsic defects in AlAs. It was found that the formation energy of AsAl is lower than others, so undoped AlAs is n-type semiconductor.