Preparation Of Tin Oxide Thin Film Gas Sensor By Magnetron Sputtering

SnO₂ is one of the most widely used gas sensitive materials at present.Its crystal structure belongs to the square rutile structure,which has good reliability and mechanical properties,and is reversible to the detection gas.SnO₂ nanofilm has the advantages of large specific surface area,low energy consumption and easy to be combined with other planar processes.It is an ideal material for preparing integrated micro gas sensors.In this paper,a dense layer of SnO₂ nanofilm was deposited on p-Si substrate by magnetron sputtering method to form a SnO₂/Si heterojunction.By loading Ag particles and composite metal oxide In₂O₃ on the surface of SnO₂ film,the sensitivity of the sensor was improved and the response/recovery time was shortened.The main research contents and results are as follows:Firstly,SnO₂ films with different sputtering pressure,film thickness and sputtering power were prepared by controlling parameters,and the effects of different experimental parameters on film quality were analyzed.The sputtering power was set as 30 W,and the sputtering pressure was set as 0.1 Pa,1.0 Pa and 2.5 Pa,respectively.The experimental results show that the heterojunction has better gas sensitivity and the overall performance is the best at the sputtering pressure of 2.5 Pa.When the sputtering pressure is 2.5 Pa,the thickness of the film is changed,and the thickness of the SnO₂ film is set to 25 nm,40 nm,60 nm and 80 nm respectively.According to the experimental data,when the film thickness is 40 nm,the response to the reaction gas is the best,and the gas sensitive performance is the best.Secondly,a layer of metal Ag is deposited on the surface of the SnO₂ film by magnetron sputtering,and Ag particles are formed by annealing.The experimental results show that at room temperature,the films loaded with Ag particles have improved sensitivity to ethanol and acetone.When the sputtering time of Ag is 80 s,the response value is the highest;when the test temperature is 300℃,the sensor has the highest response value to ethanol.The highest,and has good repeatability,the response value of 10 ppm ethanol can reach 2.0,with good detection limit and selectivity.Finally,composite films with different film thickness ratios were obtained by depositing In₂O₃ with different thicknesses on the surface of SnO₂ films（the ratios of SnO₂ and In₂O₃ were 1:1,2:1,3:1,and 4:1,respectively）.The experimental results show that at room temperature,the sensitivity of the composite film to ethanol is significantly improved,and the response/recovery time to the reaction gas is significantly reduced;when the test temperature is 400℃,the response value to ethanol is the highest,and the composite films with different ratios have good Repeatability,the response to 10 ppm ethanol gas can reach 4.5.In summary,this paper mainly studied the gas sensitive characteristics of SnO₂/Si heterojunction at room temperature and after heating,and the improvement of the gas sensitive performance of single SnO₂ gas sensor by carrying metal Ag nanoparticles and compound other metal oxides,providing reference for the preparation of high sensitivity and low power consumption gas sensor.There are 45 figures,7 tables and 81 references.