Nonuniformity has been demonstrated of commercially available p-type 6H SiC bulk and epitaxial wafers by using photoluminescence (PL) mapping at room temperature. Three deep-level PL bands with peaks at 1.95, 1.35 and 1.05 eV have been detected for the first time besides the near band-edge emission associated with Al acceptors. The intensity variations of these bands on wafers differ depending on the sample. A circular pattern appeared corresponding to the dark core region of the wafer. A one-sided intensity pattern was observed in an epitaxial layer, which is speculated to reflect inhomogeneous gas flow and/or temperature gradient in the reactor. We believe that the ability of the present technique for the characterization of nonuniformity contributes greatly to the improvement of the crystalline quality of SiC.
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