Study of the impact due to spin-orbit coupling effect on the optical properties of InP1−xSbx alloys in mid-infrared applications: A DFT approach

Abstract

The optical properties of InP1−xSbx(at, x = 0.25, 0.50 and 0.75) supercell structure have been computed utilizing TB-mBJ scheme under FP-LAPW method employing WIEN2K package. The study of optical properties for the supercell structures includes the analysis of absorption, reflection, refraction and energy losses characteristics with increasing incident photon energy. This study also claims the non-negligible impact of SOC (Spin-orbit Coupling) effect in the supercell structures due to enhanced Sb incorporation. The refractive index and extinction coefficient values are obtained to be significantly higher for the supercell structures. A resemblance between real (imaginary) part of the complex dielectric constant with complex refractive index has been interestingly observed. An enhanced smoothness of the absorption characteristics curve along with distinct peak values occurs due to the impact of SOC effect in the supercell structures with increased Sb incorporation. The presence of SOC effect led to obtain significant higher values of optical conductivity and reflection coefficient, thereby signifying the material to be lossy in nature. The occurrence of distinct plasma frequency peaks has been observed in the supercell structures due to an enhanced degree of SOC effect. Most interestingly, with increase in Sb incorporation in the supercell structures, a blue shift has been observed in each of the optical characteristic curves.