The Study On Co-sputtering Preparation And Gas Sensing Property Of Sn-doped WO₃Thin Films

WO₃is N-type metal oxide semiconductor material has a sensitivity of its oxidizinggases of NO_x, O₃, SO₂, and reducing gas H₂S, H₂, NH3. Gas sensing properties of WO₃gas sensitive materials also need to improve. This article by appropriate addition of Snelement in WO₃prepared Sn-doped WO₃films, test their NO₂gas sensing properties oflooking for the best film preparation conditions.In this paper, the double-target magnetron reactive sputtering method, the metaltungsten target using DC sputtering, metallic tin target using RF sputtering, The film at350℃、450℃annealing. Step meter, double beam UV/visible/near infraredspectrophotometer, and X-ray diffraction characterization of the instrument on thepreparation of WO₃thin film test,and study of WO₃thin film samples of thickness,optical properties, microstructure. The results showed that: With the partial pressure ofoxygen increases the deposition rate is smaller, with the Sn sputtering power increases,the deposition rate is larger. As the annealing temperature, the thin film from amorphousto crystalline transition.20%of the oxygen partial pressure of pure WO₃samplescrystallization heat treatment at450℃for the best quality monoclinic structure, and inthe direction （200） preferred orientation growth.Resistance-type Gas sensing properties of WO₃films and Sn-doped WO₃filmswere studied, the test compares the film samples prepared under different conditions of200ppm NO₂gas sensing sensitivity. The test results show that high sensitivity to NO₂in the film samples after annealing at450℃and250℃working temperature;Thepartial pressure of oxygen of30%of the film sample at250℃operating temperature,the higher NO₂sensitivity;Sn sputtering power of20W film samples in the operatingtemperature of250℃higher NO₂sensitivity. Experiments show that the partialpressure of oxygen of30%, Sn sputtering power of20W, the samples annealed at450℃has good selectivity to NO₂in250℃of200ppmNO₂gas sensitivity, response time of22s, the recovery time for156s. The experiments also WO₃thin film materials, pressuresensitive gas sensing tests showed that WO₃200ppmNO₂gas at room temperature, apressure sensitive gas sensing properties.