Preparation And Opto-electrical Of Nb Doped SrTiO₃ Thin Films By Sol-gel Method

Transparent conductive film is a kind of thin film material with high transmittance to visible light and good electrical conductivity properties.It is widely used in lots of fields,such as the liquid crystal display of mobile phone,camera and TV.At present,the dominant transparent conductive oxide film in the market are the oxide materials with indium element represented by ITO film.With the wide application of various electronic products with displays,the consumption of indium is bound to accelerate.However,the available indium resources are extremely limited.Therefore,it is of great application value to find a non-indium transparent conductive film with excellent properties.SrTiO₃ is an indirect band gap semiconductor material with perovskite structure and has high transmittance to visible light.In recent years,it has been found that SrTiO₃ doped with Nb element shows relatively good electrical properties,which makes it have a significant application prospect in the field of transparent conductivity.However,there are still different conclusions about the optimal doping content of Nb in SrTiO₃,and the heat treatment process of Nb-doped SrTiO₃ thin film prepared by chemical wet method reported in literature is not very clear.In view of the above reasons,this paper will systematically study the heat treatment process of Nb-doped SrTiO₃ film based on sol-gel method,design the optimal Nb doping content based on the cluster-plus-glue-atom model,and then study the influence of Nb doping concentration on the photoelectric properties of SrTiO₃ film through the experimental system.The optimum doping concentration of Nb was elucidated by comparing experimental results with theoretical results.The specific research contents are as follows:Firstly,the heat treatment process of Nb doped SrTiO₃ thin films was systematically studied by sol-gel method.By studying the phase,morphology,electrical and optical properties of the films prepared with different parameters,it is found that the best pyrolysis temperature and annealing temperature of Nb-doped SrTiO₃ films in atmospheric atmosphere are 650°C and 850°C,respectively.It is also found that when the pyrolysis temperature is not higher than 550°C,the prepared films will not crystallize even after annealing at 850°C for 10 min.In addition,the conductivity of Nb-doped SrTiO₃ film prepared in atmospheric atmosphere is very poor,and it needs H₂ atmosphere annealing to have better electrical properties.It is found that the films annealed at 700°C for 6 min in H₂ atmosphere have excellent photoelectric properties.Then,the optimum doping concentration of Nb in SrTiO₃ thin films was studied by combining theory with experiment.Firstly,the best possible doping concentration of Nb in SrTiO₃ was calculated based on cluster-plus-glue-atom model.Then,some Nb doped SrTiO₃films were prepared according to the doping concentration nodes calculated by the model.By analyzing the phase structure,morphology,optical and electrical properties of these films,it is concluded that the film has the best photoelectric property when Nb doping concentration is12.5at.%.The experimental results are consistent with the optimal doping concentration calculated theoretically.In conclusion,this paper systematically studied the heat treatment process of Nb-doped SrTiO₃ thin film and the optimal Doping concentration of Nb based on sol-gel method,which realized the performance optimization of Nb-doped SrTiO₃ thin film and provided a basis for the wide application of Nb-doped SrTiO₃ transparent conductive film in the future.