Studies of Defects and Thermal Conductivity of Mixed Polytype in 6H-SiC Single Crystal by Polarized Optical Microscopy, Light Scattering Tomography, and Thermal Microscopy

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This study was performed to investigate the defects and thermal conductivity of a mixed polytype of 6H-SiC single crystal using polarized optical microscopy (POM), light scattering tomography (LST), and thermal microscopy. First, we used Raman scattering spectroscopy to identify the mixed polytype, and we observed 15R-SiC mixed in a 6H-SiC single crystal. Next, as POM enables color distinction, we could clearly examine the defects in the mixed polytype area and border of 6H-SiC and 15R-SiC. Furthermore, we successfully presented defects that existed in the mixed polytype area and border in three-dimensional (3D) display by 3D light scattering tomography (3D-LST). Finally, we confirmed that there is a difference between the thermal conductivities of mixed polytypes of a 6H-SiC single crystal by thermal microscopy. The thermal conductivities of 6H-SiC, 15R-SiC, and their mixture were 475, 427, and 396 W m-1 K-1, respectively. These differences in thermal conductivity are caused by the existence of defects and the difference in carrier mobility between all polytypes.
2010-09-25