Growth And Optical Conductivity Properties For Mnal2s4 Single Crystal Thin Film By Hot Wall Epitaxy Method

A stoichiometric mixture of evaporating materials for MnAl2S4 single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, MnAl2S4 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were 630 degrees C and 410 degrees C, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The temperature dependence of the energy band gap of the MnAl2S4 obtained from the absorption spectra was well described by the Varshni's relation, E-g (T) = 3.7920 eV -(5.2729 x 10(-4) eV/K) T-2/(T + 786 K). In order to explore the applicability as a photoconductive cell, we measured the sensitivity (gamma), the ratio of photocurrent to dark current (pc/dc), maximum allowable power dissipation (MAPD) and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in S vapour compare with in Mn, Al, air and vacuum vapour. Then we obtained the sensitivity of 0.93, the value of pc/dc of 1.10 x 10(7), the MAPD of 316 mW, and the rise and decay time of 14.8 ms and 12.1 ms, respectively.