Initial investigations into the MOS interface of freestanding 3C-SiC layers for device applications

This letter reports on initial investigation results on the material quality and device suitability of a homo-epitaxial 3C-SiC growth process. Atomic force microscopy surface investigations revealed root-mean square surface roughness levels of 163.21 nm, which was shown to be caused by pits (35 µm width and 450 nm depth) with a density of 1.09 × 105 cm-2 which had formed during material growth. On wider scan areas, the formation of these were seen to be caused by step bunching, revealing the need for further epitaxial process improvement. X-ray diffraction showed good average crystalline qualities with a full width of half-maximum of 160 arcseconds for the 3C-SiC (002) being lower than for the 3C-on-Si material (210 arcseconds). The analysis of C–V curves then revealed similar interface-trapped charge levels for freestanding 3C-SiC, 3C-SiC on Si and 4H-SiC, with forming gas post-deposition annealed freestanding 3C-SiC devices showing DIT levels of 3.3 × 1011 cm-2 eV-1 at EC-ET = 0.2 eV. The homo-epitaxially grown 3C-SiC material’s suitability for MOS applications could also be confirmed by leakage current measurements.