Study On The Gas Sensing Properties Of Zinc Oxide By Doping And Modifing

Metal oxide semiconductor gas sensors are available detection materials of contaminating gases.However,there are still some problems such as low sensitivity,poor selectivity and high working temperature and limited service time under measuring low concentration gas.Therefore,preparing high response and long life-span gas sensing materials,investigating the mechanism of gas sensing performances and then manufacture highly-stablity sensor devices are the key issues for modern semiconductor gas sensors.This paper presents that different types of doping and modification of ZnO are synthetized by static method.The gas sensing properties and applications of the as-produced materials are investigated systematically.The main research contents and results are as follows:(1)CdO-Mn-ZnO and Au-Ni-ZnO were prepared by coprecipitation method,and ZnO nanorods were prepared by plasma.XRD,SEM,XPS and other methods were applied to characterize the synthetic materials.It is found that Mn and Ni are doped into the ZnO lattice respectively,and demonstrated in different levels of lattice distortion.CdO,Au and Zn are doped out of ZnO lattice,and enhanced the catalytic performance and surface activity,while Zn introduces more crystal defects.(2)The gas sensing properties of sensor samples(including sensitivity,selectivity,response and recovery time)were measured by static test system.The results suggested that 1-2.2mol%,Mn-ZnO(1-2.2MZO)and 10mol%CdO-1mol%Mn-ZnO(10Cd1MZO)possesses good selectivity for acetone and ethanol respectively.Ni probably increase the gas sensing properties of acetone,and Au may further promotethis performance as second phase.The addition of Zn increases the crystal defects and could improves the response to ethanol.(3)The application of sensor materials are analyzed by combing with the fabricated sensors(including field effect transistor sensors,sensor arrays,and novel sensor circuits).The field effect transistors play a role in amplifying low concentration gases.2.2MZO and 10Cd1 MZO can form a simple array of ethanol acetone sensors.By detecting the gas alarm,it can be implied that the device can react quickly under the conditions of different gas concentrations and release the alarm in time.