Optical and Photoelectric Properties of Planar Structures Obtained by Thermal Annealing of Ga_2S_3 Plates in Zn Vapors

摘要

Ca_2S_3 single crystals have been obtained by chemical vapor transport (CVT) in iodine vapors. The Ga_2S_3 compound was synthesized from Ga and S taken in stoichiometric quantities. The compound has been subjected to long term thermal annealing (TA) at the temperatures of 850 and 1070 K for 6 to 60 h in Zn vapors. After TA the natural surface of Ga_2S_3 single crystals contain a cover layer. The photoluminescence, photoconductivity and electrical conductivity of this layer depend on treatment conditions (temperature and duration). Electrical conductivity of these samples is 3-5 magnitude orders higher than for untreated crystals. The treated single crystals contain both Ca_2S_3 and ZnS crystallites. Thermal annealing of Ga_2S_3 crystals in Zn vapors leads to shifting of fundamental absorption edge toward low energies and absorption coefficient increase in the spectral region of 2.4-3.0 eV.