Wei Zhang,Xinhui Yang,Zhiwei Qu,Zirui Liu,Youjin Zheng,Xiangmin Zhao,Xue Wang
Ga-doped ZnO (GZO) powders were synthesized by chemical coprecipitation . GZO powders were annealed in O 2 , Ar, N 2 , and H 2 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, N 2 , H 2 atmosphere have excellent electrical resistivity, while GZO annealed in O 2 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 (V O ) and doped Ga, the blue and green emissions (around 500 nm) are originated from V O defects. The density of V O defects and the effective doping rate of Ga will be enhanced when GZO annealed in Ar, N 2 , H 2 atmosphere.
N-butanol gas is a common volatile organic compound (VOC) that can pose a threat to human health and pollute the atmospheric environment. However, the n-butanol gas sensors suffer from low response and selectivity. Herein, we synthesized the Ga-doped ZnO (ZOG) sensors by one-step hydrothermal treatment and subsequent calcination. The oxygen vacancies content of 1-ZOG has increased by 46 % compared to pure ZnO. Rich oxygen vacancies can increase the response signal of 1-ZOG to 174.78 in darkness for 100 ppm n-butanol, which is 2.4 times that of ZnO. Furthermore, the gas sensing performance of 1-ZOG is improved by light excitation. Under UV irradiation, the response of 1-ZOG sensor to 100 ppm n-butanol is 3.6 times that of pure ZnO, up to 636.81. Meanwhile, the response signal of 1-ZOG to n-butanol is at least 6.32 times that of other gases under UV light, showing ultra-high selectivity. This study proved that both Ga doped and photo-excited are effective strategies for improving the sensitivity and selectivity of ZnO based gas sensors.
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