THE ROLE OF EXCESS SILICON AND IN-SITU ETCHING ON 4H-SIC AND 6H-SIC EPITAXIAL LAYER MORPHOLOGY

Specular 6H and 4H silicon carbide epitaxial layers have been grown us ing optimized in situ pre-growth and steady state growth conditions. T his study describes the impact of hydrogen and HCl etching on SIC surf aces prior to growth nucleation. Propane and HCl overpressures are sho wn to control the appearance of Si droplets and etch pits on SiC surfa ces thereby strongly impacting subsequent epitaxial layer morphology. After optimization of the SiC epitaxial growth process the majority of the remaining morphological defects observed in SiC epitaxial layers are shown to emanate from the substrate surface.