Improvement Of Gas Sensitivity Of ZnO Gas Sensor By Violetrays Radiation

ZnO nanoparticals were produced by renovated hybrid induction and laser heating,then fabricated thick film gas sensors. Under violetrays radiation (wave length: 370-395nm), gas sensing properties for ethanol at lower work temperatures were measured using distribution in static state. By mixing Sb2O3, TiO2 and WO3 to ZnO, the effects on phase constituents, resistance and gas sensor sensitivities to ethanol by doping were studied.Under violetrays radiation, ZnO-semiconductor gas sensors' conductance increased. What's more, gas sensing properties and response properties for ethanol at lower work temperatures were improved.In order to improve gas-sensing properties of ZnO gas sensors under violetrays radiation, doping was used in gas sensitive materials. By studying the effects of sintered temperature and contents on gas sensor sensitivities, it was found that Sb2O3, TiO2 and WO3 doping could increase the sensitivities; the optimum mixture had been obtained. The optimal sintered temperatures of ZnO-Sb2O3 and ZnO-TiO2 gas sensors were 450℃. The optimal content of Sb2O3 and TiO2 were 1% and 10% respectively. The optimal parameters of ZnO-WO3 were 650℃and 1%. The gas sensor of containing 10% TiO2 sintered at 450℃had the better gas-sensing properties under violetrays radiation.It can be shown from experimental results, with increasing of the violetrays'strength and concentration of ethanol, gas sensitivity increased. Gas sensing properties of ZnO-WO3 for ethanol were better than for benzene under 24W violetrays radiation.The paper has three parts. In the first part, connecting the formation mechanism of gas sensor with violetrays radiation, the formation mechanism of improvement of sensitivity of ZnO based semiconductor gas sensor by violetrays radiation had been summarized before the purpose and importance of our research have been presented. In the second part, gas-sensing properties of ZnO gas sensors under violetrays radiation were investigated. In the third part, the influences of doping on phase constituents, resistance and gas-sensing properties were studied. Different doping materials and their effects on gas sensitivities were compared. The formation mechanism was discussed.