Research On Electrical Properties Of Tin Dioxide Based On Density Functional Theory And Its Film Preparation

Tin Oxide?SnO₂?is a wide bandgap semiconductor metal oxide material and has been widely studied due to its good gas sensing properties.At present,there have been a lot of experimental studies on how to improve the gas sensitive properties of tin dioxide,but there are relatively few studies in theoretical calculations.In recent years,due to the improvement of the theoretical basis and the development of hi-tech computer technology,the first-principles simulation method based on the density functional has become an important research method in computational material science research.In this dissertation,a large number of studies and analyses have been conducted on the mechanism of doping of zinc and the mechanism of surface oxygen adsorption based on density functional theory.At the same time,Tin Oxide thin films have been prepared and characterized by magnetron sputtering.Firstly,a crystal structure model of Tin Oxide was created,and the energy band characteristics of Tin Oxide were analyzed by calculation results.In addition,an atomic substitution method was used to establish a Tin Oxide crystal structure model with different Zn doping concentrations.The calculated energy band structure and density of states were found to have low zincdoping to reduce the energy band gap and enhance the conductivity characteristics of Tin Oxide,and when the doping concentration is greater than 25%,the Tin Oxide crystal structure distortion occurs,the bandgap increases,and the conductive properties weaken.Then,Tin Oxide?110?surface structure model was studied and analyzed.By comparing the formation energy of vacancies at different oxygen vacancies,it was determined that the Tin Oxide?110?surface most likely loses the surface bridge oxygen O_2c,and this results in oxidation.Tin?110?surface reduction structure model.And the two adsorption models for establishing oxygen on the reduction?110?plane of Tin Oxide were vertical adsorption and parallel adsorption.The analysis of the surface structure,density of states,and number of electron populations before and after the two adsorption structures revealed that when oxygen is adsorbed on the surface of the Tin Oxide crystal,electrons are transferred and the resistance of the Tin Oxide surface changes.Disclosed gas sensing mechanism of tin dioxide.From the calculated adsorption energy,it can be seen that the best adsorption method is parallel adsorption.At this time,oxygen is adsorbed on the surface of the material in the form of ions.The larger the amount of electron transfer,the more obvious the surface resistance changes.Finally,Tin Oxide thin films were prepared by magnetron sputtering.The films were studied by XRD and SEM.The effects of annealing temperature and different Zn doping concentration on the surface structure of the thin films were analyzed.