Theoretical study on optical and thermoelectric properties of the direct band gap α/β-Ca2CdAs2 pnictide semiconductors

Abstract

This article reports the utilization of the density functional theory within the Perdew–Burke–Ernzerhof generalized gradient functional for the electronic structure, optical and thermoelectric properties of the α-Ca₂CdAs₂ and β-Ca₂CdAs₂ single crystals. The theoretical calculations show that both the compounds are direct band gap semiconductors with optical band gaps of 0.96 eV and 0.79 eV at the point for α- and β-phases, respectively, which demonstrate that these compounds are optically active. The total and projected density of states, electronic charge density and optical properties, such as complex dielectric function, energy loss function, absorption coefficient, reflectivity and refractive index of α/β-Ca₂CdAs₂, were studied using the abovementioned technique. The calculated results for the energy band structures are compared with experimental and other simulated data. Temperature-dependent thermoelectric properties, such as electrical and thermal conductivity, Seebeck coefficient, power factor and figure of merit, were calculated. Our results show that α- and β-Ca₂CdAs₂ compounds are suitable materials for non-linear optical properties and thermoelectric devices.