4H-SiC epilayers grown on 4º off-axis substrates at high rates usually suffer from step-bunching (very high surface roughness) or of extended triangular defects, both detrimental for device performance.
In this study we developed a novel in situ pre-growth surface preparation based on hydrogen chloride (HCl) addition at a temperature higher than that used for the growth. This pre-growth etching procedure minimizes the density of triangular defects which usually occur at low temperatures and simultaneously enables growth at a temperature low enough to avoid stepbunching. Thanks to this surface preparation step, chloride-based CVD could be used for rapid epitaxial growth of high quality layers. In this study, layers were grown at rates of 100 μm/h yielding defect free epitaxial layers with very smooth surface (RMS value of 8.9 Å on 100x100 μm2 area).