Nanoporous ZnO structure prepared by HiPIMS sputtering for enhanced ozone gas detection

Abstract

A high performance ozone gas sensor is fabricated using high power impulse magnetron sputtering (HiPIMS) process with nanoporous ZnO as the sensing material which is deposited on micro electro mechanical systems (MEMS) device. The morphology and nanostructure properties of ZnO were tested with XRD, SEM, TEM, EDS and XPS. As the sensor is tested at different temperatures, the sensor showed high sensing response at 200 °C operating temperature and with 400 °C annealed sample of nanoporous ZnO sensor. Low concentrations of ozone were chosen to obtain best possible sensing response characteristics ranging from 50 ppb to 1000 ppb. At 1000 ppb, sensor recorded a high 638% sensing response at 200 °C optimal temperature. Selectivity test and effects of relative humidity data is presented in the study, where sensor had high selectivity towards O3 gas and the sensing response showed decreasing trend with increase in relative humidity. The reason behind sensing mechanism of the nanoporous ZnO sensor is explained due to the adsorption and desorption phenomenon on the surface of ZnO sensor.