Temperature dependence of the fundamental bandgap of Cd1-xNi{pmx}Te single crystals

Abstract

We have investigated the effects of Ni substitution (0 ≤ x ≤ 0.04) on the structural and the optical properties of bulk Cd1-xNixTe single crystals grown by using the Bridgman method. X-ray diffraction patterns show that incorporation of Ni into CdTe does not significantly affect the crystalline structure of CdTe. Although the Ni incorporation does not significantly alter the crystal structure, we find that the measured bandgap varies in the range from 1.474 to 1.453 eV at room temperature. Together with the one-photon absorption coefficient, the crucial optical parameters describing the temperature dependence of the bandgap energy are determined based on three analytical models considering both thermal expansion and electron-phonon interactions. A series of our experimental results indicates that this relatively new semiconductor can be utilized for important photovoltaic applications.