Abstract: 6H-SiC is a more promising substrate than sapphire used for the growth of GaN high power devices. The influence of surface treatments such as lapping, chemi-mechanical polishing on surface properties of 6 H-SiC substrates was studied. Substrate surfaces were investigated by means of optical microscopy, atomic force microscopy, Raman spectroscopy and Rutherford backscattering spectrometry.The results show that the surface quality was improved after two-step chemi-mechanical polishing processes. Substrates after chemimechanical polishing have superior surface morphology, high transmission and least subsurface damage and the surface roughness (RMS) is 0.12nm. High quality GaN epitaxial layers on 6H-SiC substrates were obtained using a metal organic chemical vapor deposition growth technique.

Key words: 6H-SiC is a more promising substrate than sapphire used for the growth of GaN high power devices. The influence of surface treatments such as lapping, chemi-mechanical polishing on surface properties of 6 H-SiC substrates was studied. Substrate surfaces were investigated by means of optical microscopy, atomic force microscopy, Raman spectroscopy and Rutherford backscattering spectrometry.The results show that the surface quality was improved after two-step chemi-mechanical polishing processes. Substrates after chemimechanical polishing have superior surface morphology, high transmission and least subsurface damage and the surface roughness (RMS) is 0.12nm. High quality GaN epitaxial layers on 6H-SiC substrates were obtained using a metal organic chemical vapor deposition growth technique.