Infrared Spectra Study Of The Electrical Properties Of 6H-SiC

In this thesis, first the characters of SiC materials and its growth methods were resumptively introduced. Then some basic theories of the physical picture for the far infrared (F-IR) spectra and the methods of the theoretical calculation were explained. Finally, both the principle of the Fourier Transform Infrared (FTIR) spectrometer and the FTIR instrument were given.Based on the above theories, the electrical parameters of n-type 6H-SiC crystal made in china were studied using Infrared Reflectance Spectroscopy as a nondestructive and contactless method. The samples we used in this paper were growthed by PVT which is the growth method that the most present SiC crystal uses. First the Hall effect measurement was used. In this process Au/Ni was used instead of Ni to be the ohm contact material. In this way two problems can be resolved to a certain extent which are often meeting by using pure Ni to be ohm contact material. Electric conduction type , resistivity , carrier concentration and mobility were obtained from the Hall effect measurement. Then, for the reasons mentioned above about SiC, a modified classical dielectric function was proposed to fulfill this necessity. This dielectric function was used to analyze the infrared reflectance spectra obtained from experiment. We observed that the fitted spectra calculated using the function accored with the one from experiment. From that fitting some information about the optical phonon and the plasma can be obtained. Using these information the carrier concentration and mobility of SiC can be calculated. Finally the values obtained from the analysis of the infrared reflectance spectra were compared with those obtained from the Hall effect measurement. The results show that the carrier concentration from these two methods agree with each other well, while the mobility has some differences, which need to be studied further.Infrared reflectance measurement is a nondestructive and contactless method. It plays signality to characterizing SiC. There are more experiments and study of the theory we nend to continue. For the different range of carrier concentration, we need modify the dielectric function to obtain more exactitude electrical parameters.