Ab Initio Investigation of Vibrational, Optical and Thermodynamics Properties of Yttrium Arsenide

The paper reports structural, electronic, vibrational, optical, and thermodynamic properties of the cubic structure of yttrium arsenide (YAs) calculated by density functional calculations. The calculated lattice constant and electronic band gap are 6.445 and 2.49 eV (direct band gap at I" point), respectively. The stability of the cubic structure of YAs is also confirmed by phonon dispersion curve. The refractive index using the complex dielectric function of cubic YAs is 2.57 in the near-ultraviolet region. The thermodynamic properties are based on the function of temperature, which is investigated using the quasi-harmonic approximation and show that the heat capacity has been become constant above room temperature at 400 K which concludes the maximum stability of phase. Our theoretical results show that the absorption spectrum of YAs has a possible application for future devices in the near-ultraviolet region as an inner layer coating under UV absorbers, which is the main interest to optoelectronic-devices such as light emission and light detectors.