In situ substrate preparation for high-quality SiC chemical vapour deposition

In situ preparation of 4H and 6H silicon carbide substrate surfaces in hydrogen and hydrogen-propane etching systems has been studied. The etching of on-axis (0001) 6H-SiC substrates resulted in regular straight terraces and one unit high steps. The etching of on-axis (0001) 4H-SiC substrates resulted in broad terraces interrupted by large step formations. The 4H- and 6H-SiC (0001) off-axis substrates (3.5 degrees towards (11 (2) over bar 0) yield smooth etched surfaces with the exception of stripe-like defects on the 4H polytype which are shown to be related to stacking-faults. The stacking faults are suggested to be a cause for step-bunching and surface roughening. Hydrogen-etching prior to growth has been shown to improve the epitaxial layer quality both concerning defect formation and step-bunching.