In situ synthesis of flower-like ZnO on GaN using electrodeposition and its application as ethanol gas sensor at room temperature

The morphology and structure of sensing materials are extremely important to performances of gas sensor. Zinc oxide (ZnO) is a promising gas-sensing material, due to its morphology controllable fabrication. In this work, flower-like ZnO (FZnO) was synthesized on GaN by electrodeposition as sensing materials of ethanol gas sensor. FZnO consisting of ZnO nanosheets with thickness of 55 nm is in situ grown on GaN. When FZnO/GaN heterojunction is used as sensing materials for detection of ethanol, this material possesses a higher response than ZnO or ZnO composite at room temperature. In detail, the FZnO/GaN based gas sensor displays remarkable sensitivity (R-a/R-g = 26.9), when the sensor is exposed to ethanol at the concentration of 50 ppm at room temperature. Importantly, rapid response and recovery time is 12 and 9 s, respectively. Meanwhile, this sensor presents excellent selectivity and stability. In addition, detection limit of the sensor is 100 ppb. Enhancement of the sensing response is mainly attributed to the FZnO and conductivity of the GaN. These results indicate the potential applications of the as-prepared metal oxide semiconductor based GaN in the sensing field.