Far infrared studies of lattice and free carrier effects in narrow-gap semiconductors

Abstract

Far infrared (FIR) studies in narrow-gap semiconductors have attracted considerable attention because of providing information about both lattice and free carrier. Recent work of FIR reflection measurement in narrow-gap semiconductor Cd x Hg 1-x Se showed the importance of the contribution of interband term in dielectric function and the plasmon-LO phonon coupling [1]. Zn x Hg 1-x Se (ZnHgSe) crystals are mixed-compounds of zero-gap semiconductor HgSe and wide-gap semiconductor ZnSe. This mixed compounds crystallize in zincblende structure in the whole range of mole fraction x. The energy gap and the symmetry of the conduction band of the crystals depend on x. The experiments of Schubnikov de Haas effect in ZnHgSe with small x showed the strong nonlinear dependence of the energy gap on composition and the semimetal-semiconductor transition (x = 0.03) at 4 K[2]. Carrier scattering mechanisms were also reported in this material[3]. Nevertheless, little is known about the FIR studies in this material. In this note, we analyze the reflection spectra in ZnHgSe.