TeO2 doped ZnO nanostructure for the enhanced NO2 gas sensing on MEMS sensor device

Abstract

Severe health issues occur when human beings are exposed to NO2 gas, which is formed from combustion processes and reactions facilitated by sunlight. In order for safety measurements, NO2 gas sensors are highly needed at low concentration gas detections. ZnO gas sensor with the doping of TeO2 is developed using co-sputtering technique. ZnO/TeO2 heterojunction nanostructure is analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS) for structural study. Gas sensing properties were tested with Micro electro mechanical system (MEMS) devices, on which ZnO/TeO2 nanostructure is developed. This study focused on doping of 4 different variations of TeO2 with ZnO such as 0%, 2%, 4% and 8% atomic weight percentage (at.w%) of TeO2. Upon testing, 4% ZnO/TeO2 transpired to be best possible parameter for NO2 gas sensing. With maximum NO2 gas concentration of 1 ppm, 4% ZnO/TeO2 sensor exhibited 80% sensing response and with 200 ppb of minimum gas concentration, sensor had 42% response at optimal temperature of 100 oC. TeO2 doped ZnO sensor exhibits superior performance over pure ZnO sensor and has good selectivity over NO2 gas.