Optical and Photoelectric Properties of Planar Structures Obtained by Thermal Annealing of Ga2S3 Plates in Zn Vapors

Ga2S3 single crystals have been obtained by chemical vapor transport (CVT) in iodine vapors. The Ga2S3 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 1070K for 6 to 60h in Zn vapors. After TA the natural surface of Ga2S3 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 Ga2S3 and ZnS crystallites. Thermal annealing of Ga2S3 crystals in Zn vapors leads to shifting of fundamental absorption edge toward low energies and absorption coefficient increase in the spectral region of 2.4-3.0eV.