IN-SITU SUBSTRATE PREPARATION FOR HIGH-QUALITY SIC CHEMICAL-VAPOR-DEPOSITION

In situ preparation of 4H and 6H silicon carbide substrate surfaces in hydrogen and hydrogen-propane etching systems has been studied. The e tching of on-axis (0001) 6H-SiC substrates resulted in regular straigh t terraces and one unit high steps. The etching of on-axis (0001) 4H-S iC substrates resulted in broad terraces interrupted by large step for mations. The 4H- and 6H-SiC (0001) off-axis substrates (3.5 degrees to wards (11 (2) over bar 0) yield smooth etched surfaces with the except ion of stripe-like defects on the 4H polytype which are shown to be re lated to stacking-faults. The stacking faults are suggested to be a ca use for step-bunching and surface roughening. Hydrogen-etching prior t o growth has been shown to improve the epitaxial layer quality both co ncerning defect formation and step-bunching.