Complex Structure And Optical Properties Of Zno Thin Films Doped With High-temperature Annealing

ZnO is an important direct wide bandgap semiconductor material with exciton binding energy as high as 60meV,much higher than the thermal ionization energy at room temperature which is 26meV.The exciton is not easy to ionize.So it is easy to achieve efficient laser emission.It is an ideal material for preparation of short wavelength(eg.UV, violet or blue) light emitting devices.For a light-emitting material,the research on how to improve the performance of its light-emitting is of great significance to improve the efficiency of light-emitting devices.Doping is one of the principal means to affect the light-emitting properties of ZnO semiconductor thin films.At present,the single element doped ZnO thin films have been extensively studied,but the complex doped study also relatively small.In order to study the light-emitting mechanisms of ZnO thin films and the influence of codoped on the structure and optical properties of ZnO thin film,in this paper,we carried out on ZnO thin films with complex doped and high temperature annealing processing,. First the ZnO thin films have been deposited on single crystal Si substrate and TiO₂ buffer layer by the method of electron beam evaporation,and both of the two films have been annealed in the same high annealing temperature 850℃.The study found that the luminescence properties of them are different:the green light emission in ZnO thin film is stronger than it in the ZnO/TiO₂ film.There have a violet emission and a blue emission in the ZnO/TiO₂ film.This may be related to the movement of atoms from TiO₂ buffer layer and ZnO thin film inter-diffusion.The study results show that:the green light of ZnO thin films may be mainly related to oxygen vacancy,and violet emission may be attributed to the interface trap,and the blue emission may be related to the interstitial Zn,Ti-related defects such as interstitial Ti and so on.The study also found that for the Mg-Fe complex doped ZnO thin films which have been prepared on silica glass substrate by the method of Sol - gel,crystalline quality of 1%Mg and 1%Fe codoped ZnO thin film has been increased,but with the Fe doping concentration increases,the crystalline quality of ZnO thin films have decreased,the UV emission properties have reduced either,but the blue emission have increased.This may be due to higher concentrations of Fe doping would result in the extent of lattice distortion bigger in the films,and films' stress increases.As a result,the quality crystalline of ZnO thin films decline and there would be more interstitial atoms which lead to a stronger blue emission. The conclusions of this paper provide a theoretical and experimental basis for improving the structure and optical properties of ZnO thin films.They also have some reference meanings for the development of.ZnO thin film photovoltaic devices.