First-principle calculations of Debye temperature of optoelectronic LiGaS_2 and LiGaSe_2 semiconductors under different pressures

摘要

The ternary chalcogenides LiGaS_2 (LGS) and LiGaSe_2 (LGSe) are well known semiconductors and widely used for laserinduced damage thresholds (LIDT), optical parametric amplification (OPA) and other nonlinear optical (NLO) devices ininfra-red region. The first-principle calculations with local density approximation (LDA) are performed to calculate theDebye temperature of LiGaS_2 and LiGaSe_2 semiconductors. The values of longitudinal, transverse and average soundvelocities and Debye temperature are studied at 0, 10 and 20 GPa pressures and await for experimental verification. Thevalues of bulk modulus (B) and shear modulus (G) have also been calculated. The present study shows that LiGaS_2 andLiGaSe_2 both are stable upto 20 GPa pressure and become unstable afterwards. The estimated values of all parametersare in good agreement with the available known values at 0 GPa pressure.