On the Ammonia Gas Sensing Performance of a RF Sputtered NiO Thin-Film Sensor

An interesting ammonia gas sensor based on a p-type NiO thin film, prepared by a radio frequency sputtering process, is studied and demonstrated. As compared with conventional n-type metal-oxide sensors, the studied device shows comparable and good sensing performance, including a high-sensing response ratio of 289%, a lower response time of 31 s, and a lower recovery time of 78 s, under an introduced 1000 ppm NH₃/air gas at 250 °C and 350 °C, respectively. In addition, the studied sensor device exhibits a lower detection limit (<;5 ppm NH₃/air) at 250 °C. Consequently, based on these advantages and inherent benefits of low cost, chemical stability, and easy fabrication, etc., the studied NiO thin-film sensor shows the promise for high-performance ammonia gas sensing applications.