Measurement And Analysis On Optical Constants Of6H-SiC Crystal By Using Ellipsometry Technology

Spectroscopic ellipsometry (SE) is a very powerful technique devoted to the study of optical properties and morphology of a surface from the measurements of the change in polarization state of light reflected from the surface. Ellipsometer measurements consist of two quantities (T and△), which on behalf of the amplitude ratio and phase angle of deflection of the p-polarized light and s-polarized light after through the sample, respectively. The strong advantages of ellipsometry are its non destructive character, its high sensitivity, therefore, ellipsometry is widely used in the optical industry, electronics industry, biochemistry, metal materials more and more areas.The main content of this thesis is using ellipsometry technique to study the optical constants of anisotropic uniaxial crystal and process of data acquisition and analysis. In this thesis, we introduced the development history and future trends of Ellipsometry, limitations and advantages of ellipsometry technical, the ellipsometer classification as well as domestic and foreign research progress in detail; we also introduced the principle of Ellipsometry and the light propagation in the crystal material, then we get the Jones matrix of crystal material and ellipsometry equation. In the thesis, we choose an excellent representative of third-generation semiconductor6H-SiC as research sample, and its structure and property, research progress at home and abroad is introduced, and we also made a simple research and analysis on the photoluminescence properties of6H-SiC.In this thesis, the author propose a reliable measurement of crystal material, as well as data analysis methods, this is also the highlight in the thesis. We adopted the measurement with the optical axis perpendicular to the sample surface to reduce the measurement error caused by the uncertainty of the crystal optical axis direction; single-sided polishing of the sample to eliminate the back reflection caused by the depolarization effects; using multiple incidence angles measurements to reduce experimental error; calibrate the incidence angle by using a standard sample; applying mathematical inversion method and a suited error evaluation function as the basis for the analytical procedures, then design the program of ellipsometry data analysis; applying the appropriate optical model to fit the final results of the program inversion, then the reliable data was obtained.