Photoluminescence spectra of Zn_(1-x)Cd_xAl_2Se_(4-4x)S_(4x) single crystals

摘要

We investigated the photoluminescence as well as the crystal structure and optical energy gaps of the Zn_(1-x)Cd_xAl_2Se_(4-4x)S_(4x) solid solution system based on the Al-related compounds of ZnAl_2Se_4, ZnAl_2S_4, CdAl_2Se_4, and CdAl_2S_4. The single crystals of the system with 0.0 <= x <=1.0 were grown by the chemical transport reaction technique. The Zn_(1-x)Cd_xAl_2Se_(4-4x)S_(4x) crystallizes in a defect chalcopyrite structure for a whole composition and has an optical energy gap ranging from 3.525 to 3.577 eV at 13 K. The photoluminescence spectra at 13 K showed a strong emission band in the blue spectral region and a weak broad emission band in the visible region due to donor-acceptor pair recombination. The composition and temperature dependence of these bands were examined in the investigated regions. The simple energy band scheme for the radiative mechanisms of the Zn_(1-x)Cd_xAl_2Se_(4-4x)S_(4x) is proposed on the basis of our experimental results along with photo-induced current transient spectroscopy measurements.