Preparation And Gas Sensing Properties Of Gallium Oxide Based Semiconductor Materials

Metal oxide semiconductor gas sensors are widely used in practical application due to many advantages,including indoor toxic gas detection,industrial toxic gas leakage,air quality detection and medical disease diagnosis.However,some colorless and tasteless toxic gases are not easy to be detected by human beings.Long term exposure to this environment will cause great damage to human health.Therefore,it is necessary to explore a method,which can detect toxic gases efficiently,quickly and in real time.At present,there are many kinds of gas sensors,including electrochemical,optical,solid electrolyte,contact combustion and so on.Among them,the semiconductor gas sensor with the advantages of convenient preparation and good stability have been widely studied and developed.However,there are still some problems in the realization of commercialization of gas sensors.The research on the promotion of sensing performance by noble metal modification,metal oxide composite,metal doping,morphology control and other modification methods is prevailed.Ga with abundant resources in reserves is cheap in China.As the fourth generation semiconductor material,gallium oxide is widely studied and developed with more extensive application prospects than gallium nitride.Gallium oxide based metal oxides show great potential in the field of gas sensing,but there are still many shortcomings.In order to solve the above problems,we studied the modification of gallium oxide,including composite metal oxides,morphology control,noble metal modification and so on.The performance of the gas sensor is further optimized.The research results are as follows:1.In this paper,Ga-In bimetallic oxide(GIO)nanofibers were prepared by electrospinning,and then the noble metal Pt was modified on the surface of GIO nanofibers by impregnation,giving GIO nanofibers with different Pt content.The gas sensing properties of GIO nanofibers modified with different Pt contents were studied.The results show that the response of 1.2 at.%Pt-GIO gas sensor(Ra/Rg=152)to 100ppm acetone is greatly improved compared with that of GIO sensor(Ra/Rg=27).In addition,1.2 at%Pt-GIO gas sensor show the advantages of low working temperature(160?),fast response time(<10 s),and good stability,etc.,which can realize the detection of acetone exhaled breath at ppb level with the humidity resistance in high humidity(40%RH-95%RH).The improvement of gas sensing performance is due to the formation of Schottky contact between Pt and GIO,which promotes the electron transfer from GIO to Pt.In addition,the increase of the adsorbed oxygen on the surface of metal oxide attributed to the spillover effect of Pt.2.Compared with single metal oxide,composite metal oxide can improve the gas sensing performance,commonly.Among them,spinel metal oxide has been widely studied in the field of gas sensors.However,the traditional preparation methods need high synthesis temperature to overcome ion diffusion hinder.In this paper,series of spinel gallate metal oxide nanospheres were prepared by solvothermal method combined with calcination,giving Cd Ga₂O₄,Ni Ga₂O₄,Co Ga₂O₄,Cu Ga₂O₄,Zn Ga₂O₄,and Mg Ga₂O₄.The composition,microstructure,atomic valence state and pore analysis of the series of spinel gallate metal oxide were characterized by X-ray diffraction,scanning electron microscope,X-ray photoelectron spectroscopy and N₂ adsorption-desorption.The results show that this strategy can successfully prepare series of spinel gallate metal oxide.The gas sensing performance test results show that Cd Ga₂O₄ gas sensor exhibit high response(Ra/Rg=27)to 100 ppm formaldehyde with the advantages of low working temperature(120?),fast response time(1 s),good stability,and can realize the detection of 60 ppb formaldehyde.