Because SiC has large number of polytypes determined by their stacking order during crystal growth, the polytype inclusion has been a common issue during SiC growth, especially at the early stage of development of new process or new equipments. When photon is incident on the surface of SiC crystal and the energy of photon is larger than the band gap of SiC (2.9 ~ 3.3eV in the UV range), the photon excites the electron in the valence band to the conduction band. Excited electron goes to the lower states emitting heat and relaxes to the valence band emitting photon that has longer wavelength that the incident light. The phenomena that wavelength is shifted to the longer wavelength by material is called fluorescence. Thus, polytypes with different energy band gap can be identified with the fluorescence color if UV ray is incident ray with sufficient energy for excite electron in the valence band.
In this study, we observed the fluorescent color of various SiC polytypes with a lab-developed UV fluorescence equipment. The UV fluorescence is non-destructive technique to characterize the grown sample without any further sample preparations, so that this technique is applied to develop a new PVT process in the early stages. SIMS, Photoluminescence and Raman spectroscopy were used for identify the fluorescence color considering polytypes, dopants and defects. Stress mapping using high resolution X-ray diffraction and Raman spectroscopy were used for analyzing the effect of polytype formation on residual stress distribution on the grown crystal. Glazing-incidence X-ray topography using white beam were conducted for evaluating the grown SiC crystals at Pohang accelerator laboratory.