The Study Of Defect Chemistry Properties And Gas Sensing Performance Of Li Doped ZnO

Zinc oxide(Zn O), one of the most promising metal oxide semiconductors(MOS), which has a wide band gap of 3.37 e V with a high exciton binding energy of 60 me V, has found a wide range of applications. One of the most important applications of Zn O is served as a semiconductor gas sensor. For the advantages of high sensitivity, fast response and recovery time, low cost, and long-term stability, Zn O gas sensors have been widely applied to the food production, air monitoring, medical treatment and aerospace etc. We have researched the sensing performance and the electrical properties of the Zn O and Li doped Zn O by the self-designed High Throughput Screening Platform of Gas-sensing Materials(HTSP-GM). The impacts of the Li doping to the gas sensing performance of Zn O have been deeply analyzed. Based on the defect chemistry we established a gas sensing mechanism model. The model successfully illuminates the way of Li doping affect the sensing performance. We have achieved the following results.(1) We have synthesized the different content of Li doped Zn O respectively by the homogeneous precipitation method(HP) and hydrothermal method(HT). We proved the different doping behaviors of the two preparation method of Li doped Zn O by Microstructure characterization.(2) The prepared Li doped ZnO was made into gas sensing test chip by screen printing technology and the gas sensing performance and electrical properties were tested. The tests showed that the x = 0.1 Li doped Zn O prepared by homogeneous precipitation method possesses the best sensing performance and the sensitivities are up to 40.2 and 71.5 for sensing formaldehyde and methanol respectively.(3) Based on the defect chemistry theory and the results of electrical test we analyzed defect properties of the Zn O and Li doped Zn O.(4) We established a gas sensing mechanism model based on defect chemistry theory. The main point of the model is that the synergistic effect of oxygen interstitials and oxygen vacancies can significantly enhance the gas sensing performance.