4H-SiC CVD epitaxial layers with improved structural quality grown on SiC wafers with reduced micropipe density

Reduction of defect densities in SIC epitaxial materials is the key issue for a development of SiC large area devices. We report on improvement of material characteristics and Schottky barrier breakdown voltages for 4H-SiC epitaxial layers grown by chemical vapor deposition (CVD) on 4H-SiC epitaxial wafers with reduced micropipe density (RMD). Initial substrates were two 4H-SiC 8 degrees off-axis commercial wafers cut from the same boule. Micropipe filling process was performed on one wafer. CVD epitaxial layers 25 mum thick with concentration N-d-N-a = (2-4)x10(15) cm(-3) were grown on both wafers in the same epitaxial run. Structural quality of the CVD epitaxial layers was characterized by x-ray diffraction methods, x-ray topography and optical methods. X-ray topography and electron beam induced current (EBIC) technique revealed defect density reduction in the CVD layer grown on RMD epitaxial wafer. Schottky barriers made without edge termination for CVD layer grown on the RMD wafer had a breakdown voltage up to 1500 V while the breakdown voltage for the another sample did not exceed 1000 V.