Observation of the Surface Morphology on the (0001)C Facet of 4H-SiC Boules

Abstract

The surface morphology on the (000-1)C facet of 4H-SiC boules grown by the physical vapor transport method was examined in various scales (from millimeter to nanometer) using different types of microscopies such as differential interference contrast (DIC) optical microscopy and atomic force microscopy (AFM). The DIC optical microscope observation revealed that there exist three distinct morphological regions at the growth front of the 4H-SiC boules; they are facetted, non-facetted, and the intermediate region between them. The local inclination of the facet surface from the (000-1) basal plane increases toward the facet edge and then decreases over the intermediate region. AFM observations revealed characteristic step structures in these two regions and also that they are significantly influenced by nitrogen-doping. Based on the results, the formation mechanism of the facet morphology on 4H-SiC boules is discussed.