Study Of Preparation And Photoelectric Properties Of Sr₂TiO₄ Trans Parent Conduetive Thin Films

Sr2TiO4material is a kind of two-dimensional layered perovskite oxide with large energy gap, it will be an alternative of the dualistic oxide materials as a ternary compound materials for its excellent photoelectric characteristics, It can be prepared from raw materials which are cheap and abundant on the earth, its energy gap is about 3.8 eV at room temperature, it is transparent to the visible light band. Intrinsic Sr2TiO4 material is insulated, it turns into semiconductor or conductor with appropriate doping. Thus, it can be used in the field of transparent and conductive semiconductor with large energy gap, such as the electroluminescent devices and solar cells, resistance switch memories etc. Especially, Sr2TiO4 material can be used as semiconductive layer of thin film transistor for its controllable electric conduction and visible light transparency; all of these widen the application fields of transparent thin-film transistors largely. Therefore, how to get high quality transparent conductive film is the key to realize its unusual features.This paper uses the sol-gel method to prepare kinds of Sr2TiO4 powders and transparent conductive thin films. Used X-ray diffraction, scanning electron microscope, atomic force microscope to observe and analyze the surface morphology of the material. Chose the film optical tester NKD8000 and the four-point probe tester to test the photoelectric characteristics of the thin films. The influences to photoelectric characteristics of the films after adding PVP and doping the benefactor impurities are also discussed.Tried orthogonal design method to optimize the process parameters of powder materials, analyzed the influences of forming the material by changing the usage amount of water, acid and the heat treatment temperature. It shows the material has better structure in the experiments when the ratio of water to strontium is 1.5:1(mole ratio) and to acid is 38:1 (volume ratio), annealing temperature is at 850℃.After studying the photoelectric characteristics of Sr2TiO4 thin films prepared by using the sol-gel method, the result suggests a significant improvement of surface topography and optical properties when adding PVP at the ratio of 0.4% mole to strontium. The study also shows that the doping of La can improve the surface morphology and photoelectric characteristics of the Sr2TiO4 thin films.