| Due to the disadvantages such as poor selectivity,high operating temperature,and poor long-term stability,the development and application of semiconductor gas sensors are greatly imitated.Aiming at the problems of traditional oxide semiconductors,SnO2/CuO and SnO2/WO3 two-dimensional porous composite nanofilms and BiFeO3 two-dimensional porous nanofilms has been successfully prepared by magnetron sputtering using two-dimensional colloidal crystals(PS spheres)as template,the corresponding gas sensing properties of those films were tested and analyzed.The specific works are as follows:(1)The SnO2 two-dimensional porous nanofilms have been constructed by using the two-dimensional colloidal crystal as template,which exhibits high response and good selectivity to H2S at 100 ?.By adjusting the pore size of the PS sphere and the thickness of the porous film,the controllable sensing performance can be realized.The gas sensing properties of the SnO2/CuO two-dimensional porous composite nano-film sensor to H2S at different temperature and concentration were further studied.The results indicate that the sensitivity of the SnO2/CuO gas sensor to 25 ppm H2S can be as high as 594 at 50 ?,which is around five times higher comparing to single SnO2,and the sensing mechanism of SnO2/CuO sensor is further analyzed.(2)The SnO2/WO3 two-dimensional porous nano-film based sensors were prepared and found they displayed good gas sensing responses to NO2at 50 ?,which is superior to single SnO2.The effect of WO3 thickness on the gas sensing properties of SnO2/WO3 sensor was further studied,verifying the effect of film thickness on sensor performance.The thickness-dependent gas sensing enhancement mechanism are further analyzed and discussed.(3)BiFeO3 two-dimensional porous nano-films were obtained by magnetron sputtering using colloidal crystal as template and applied to the gas sensors.It was found that the sensor shows obvious response to ethanol at 100 ?.The effects of film thickness and annealing temperature on the gas sensing properties of BiFeO3 were investigated.The results show that the 100 nm BiFeO3 annealed at 600 ? exhibits the best response to C2H5OH.In order to further improve the gas sensing characteristics,surface plasma treatment was carried out.It was found that the gas-sensing response of the treated BiFeO3 film was significantly improved,and the sensing performance was closely related to the power and time of plasma treatment.Through the further characterization by surface element state analysis,a gas-sensing enhancement mechanism based on plasma surface treatment is proposed. |
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