The Preparation Conditions Of Tio <sub> 2 </ Sub> Thin-film Optical Properties

With the rapid development of science and technology and film industry,different needs had brought forward to the film technology and film material for all kinds of requirements.In order to determine the properties of film,all kinds of research methods and test means had been brought forward,ellipsometry has high testing sensitivity and accuracy,widely used in research the properties of thin film.Study from the effect of the preparation conditions on transmittance and optical parameters of amorphous TiO₂ film,transmittance and optics parameters of thin film are tested by Shimazu UV-3101PC spectrophotometer and JobinYvon UVISEL spectroscopic ellipsometry,respectively. The progressive fitting method is used to improve the elliptical polarization parameters fitting accuracy,analysis of rationality of a new physical model is based on New Amorphous formula (NAF) and the effect of the preparation conditions on transmittance and optical parameters of amorphous TiO₂ film are detailedly studied,respectively.This work has practical value in using spectroscopic ellipsometry obtain the optical parameters,and prepare high refractive index of amorphous TiO₂ film.The thesis includes four chapters as follows:In Chapter 1,introductions to the application of the film material,the development of the film technology,and several methods to determine the optical constants of film material are established.The main works of this thesis is also involved.Chapter 2,Chapter 3 and Chapter 4 are the main body of the thesis.In Chapter 2,we introduce the instruments in testing experiment and the preparation of amorphous TiO₂ film deposited by electron-beam evaporative deposition.Then we discuss the steps of preparations and performance test and these points for attention.In Chapter 3,the progressive fitting method is presented well in fitting ellipsometric data to the films optical parameters take examples of TiO₂ and SiO₂ films.It proves that the progressive fitting had method minimized the value of the residue parameter x²,which was used to describe how close the generated data fit to the experimental ones.In other words,the optical parameters of the films got by the method are more accurately.At the stage of model establishment for elliptical polarization parameters take TiO₂ film as example,a new physical model is based on New Amorphous formula(NAF),which is presented well in fitting spectroscopic ellipsometric data to the film optical parameters.At the same time,Cauchy model was applied to test the result of this new model.Therefore,NAF dispersion formula could be applied to describe the TiO₂ optical thin film.In Chapter 4,we study the effect of the preparation conditions on transmittance and optical parameters of amorphous TiO₂ film.Influence of substrate temperature and working pressure on the optical properties of TiO₂ film as follows:1,As substrate temperature rising,the transmission spectrum of TiO₂ film gradually decrease, and its extreme points are moved to the short wave direction,this fully explains that the refractive index of the film is increased with the substrate temperature rising.These Phenomena are proved well in the results of ellipsometry.2,With the working pressure decreasing,the transmission spectrums of TiO2 film gradually decrease,and its extreme points are also moved to the short wave direction,its shows that that the refractive index of the film is increased with working pressure decreasing.And these Phenomena are also proved well in the results of ellipsometry.Therefore,high refractive index of amorphous TiO₂ film is obtained by increasing the substrate temperature and decreasing the working pressure.