Investigations On Fabrication,Characterization And Optoelectronic Properties Of In And S Doped Tin Dioxide Thin Films

At present,the wide bandgap semiconductor materials is one of hotspots in the field of semiconductor materials research,known as the third generation of semiconductor materials,mainly including diamond,Si C,Ga N,SnO₂,Zn O,etc.It has an important application prospect in high frequency devices,high temperature electronic devices,high power devices and so on.Tin dioxide?SnO₂,Eg = 3.6 3.8e V?is a kind of wide bandgap materials,which has high visible light transmittance,good thermal stability,low resistivity,high exciton binding energy,low cost and many other advantages,widely used in solar cells,light-emitting diodes,gas sensors,liquid crystal displays and so on.With the increase of the market demand of transparent p-n junction,the preparation of stable and superior performance of p-type transparent conductive film is required.But at present the most transparent conductive films including tin oxide thin films are n-type conductive.Now there are few p-type transparent conductive films,this is because low acceptor impurity solid solubility and high ionization energy.In the paper,we prepared p-type transparent conductive film to use co-doping methods.On the one hand,the atom radius of indium is close to the atom radius of tin.It can improve the solid solubility of indium acceptor.On the other hand,the electronics of sulfur and oxygen are equal,replacing O with S can improve the top of valence band level position,it can reduce ionization energy of indium acceptor.So tin oxide thin films are p-type conductive.In this paper,we prepared SnO₂:In and SnO₂:S thin films as well as SnO₂:S:In thin films by using magnetron sputtering and thermal treatment technology and then characterized and studying their photoelectric properties.In addition,we have successfully prepared p-type transparent conductive semiconductor film.The main research contents are as follows.Firstly,we prepared SnO₂ thin films on clean quartz glass by using radio frequency magnetron sputtering technology and then we obtained the pure SnO₂ nanocrystalline thin films by thermally treating the SnO₂ thin films.The test results of X ray diffraction,Raman spectroscopy and UV-Vis absorption spectra show that the sputtering power and the sputtering time affect the film formation rate and film quality.Moreover,after the heat treatment at different temperatures,the crystallinity of the films decreases and the optical band gap becomes larger and the optical absorption spectrum has a blue shift,but the conductivity is better with the increase of annealing temperature.Secondly,on the basis of the preparation methods of pure SnO₂ thin films,SnO₂: In and SnO₂: S thin films and co-doped SnO₂ thin films were also prepared.The test results of X ray diffraction,Raman spectroscopy,X ray photoelectron spectroscopy,and UV-Vis absorption spectra show that with the increasing doping concentration,the crystallinity of the film decreased and the optical band gap became smaller.Optical absorption spectra appear red shift phenomenon.Besides,Sulfur and indium co-doped SnO₂ thin film sample was p-type conductive.