Influence Of Magnetron Sputtering Process On The Stability And Sensitivity Of WO₃ Thin Film Gas Sensor

As a typical n-type semiconductor material,tungsten trioxide（WO₃）is widely used in hydrogen sulfide（H₂S）gas detection.At present,the thick-film WO₃ gas sensor prepared by traditional techniques such as screen-printing shows poor repeatability and stability in the test,which affects its practical application.Magnetron sputtering has become one of the ideal methods for preparing WO₃ films because the thin films fabricated by it have the advantages of precise and controllable thickness,uniform and dense particle distribution,stable and orderly nanostructures,and good adhesion to the substrate.This paper focuses on the stability of WO₃ thin film gas sensor,and DC magnetron sputtering was used to prepare WO₃ thin films under different process parameters（sputtering time,sputtering power,sputtering pressure,Argon oxygen flow ratio,deposition temperature）,and the characterization of XRD,AFM and SEM were carried out to reveal the influence of magnetron sputtering process parameters on the thickness,particle distribution,surface roughness,oxygen vacancies and microcracks of WO₃ films.On this basis,the quantitative evaluation indicator of the stability of WO₃thin film gas sensor is defined,that is,the fluctuation deviation of response value and the baseline drift rate,and the influence of magnetron sputtering process parameters on the stability of WO₃ thin film gas sensor was studied,and the optimal magnetron sputtering process parameters for the high stability WO₃ thin film gas sensor were determined as sputtering time 10 min,Argon oxygen flow ratio 60:30,sputtering power 30 W,sputtering pressure 3.4 Pa,and deposition temperature 25°C.Under this sputtering condition,the particle distribution of the WO₃ thin film material is uniform and dense,and the corresponding gas sensor exhibits excellent gas sensitivity to H₂S at a working temperature of 250°C.The response value of the sensor to10 ppm H₂S is 40.1,the fluctuation deviation of response value is only 1.0%,and the baseline drift rate is 2.0%,showing good short-term stability.In addition,during the two-month test,the rate of change in response value is 3.1%,which indicates it has good long-term stability.Under the optimal process,the WO₃ film with nano-columnar structure was prepared by glancing angle technique.Although the film has a larger specific surface area and is oriented to a more active（002）plane,the fluctuation deviation of response value is 1.0%,and the baseline drift rate is 1.0%,which still maintains the high stability,the response to10 ppm H₂S is 2.4 times higher than before.In summary,this paper focuses on the stability of gas sensor,and a high-stability WO₃thin film gas sensor was obtained by adjusting the parameters of the magnetron sputtering process,and the response value of WO₃ gas sensor was further improved by glancing angle technology,then the H₂S gas sensor with high stability and high sensitivity has been successfully prepared.