Influence of annealing atmosphere on optical and electrical properties of Ga-doped ZnO powders

Ga-doped ZnO (GZO) powders were synthesized by chemical coprecipitation. GZO powders were annealed in O2, Ar, N2, and H2 atmosphere, and the effects of annealing atmosphere on their structure, optical and electrical properties were systematically studied. The results show that the optical and electrical properties of GZO powder were highly influenced by annealing atmosphere. GZO annealed in Ar, N2, H2 atmosphere have excellent electrical resistivity, while GZO annealed in O2 atmosphere has poor electrical resistivity. According to the annealing contrasted of GZO in different atmosphere, the lower resistivity of GZO is, the lower reflectivity will be. The blue shift of ultraviolet emission (385 nm) in photoluminescence of GZO is related to oxygen vacancy (VO) and doped Ga, the blue and green emissions (around 500 nm) are originated from VO defects. The density of VO defects and the effective doping rate of Ga will be enhanced when GZO annealed in Ar, N2, H2 atmosphere.