Growth of smooth 4H-SiC epilayers on 4° off-axis substrates with chloride-based CVD at very high growth rate

4H-SiC epilayers grown on 4° 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 reduce step-bunching. Thanks to this surface preparation step, chloride-based chemical vapour deposition (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 100 μm × 100 μm area).

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► HCl in situ etching at high temperature prevent triangular defects in SiC epilayers.
► High growth rate of 100 μm/h obtained on 4H-SiC 4° off-axis substrates.
► Very smooth layers obtained by growth at reduced temperatures.