Study of SiC polytype heterojunctions

The results of a study of the chemical vapor deposition (CVD) growth and characterization of SiC polytype heterojunctions using ON-AXIS 4H and 6H SiC substrates are presented. Characterization results along with a pre-growth hydrogen/propane etch study were used as a baseline for developing a growth process for the SiC polytype heterojunctions. Grown heterojunctions show almost no polytype inclusions. An oxidation study to map polytype inclusions in the layers grown under different conditions show a high (>95%) polytype homogeneity. Transmission electron microscopy (TEM) shows no visible defects and/or columnar growth features. TEM diffraction patterns obtained are very strong, further indicating crystalline 3C–SiC epitaxial layers. The FWHM of the X-ray scans are very narrow, between 0.01 and 0.02°, an excellent figure further indicating single crystalline 3C–SiC epitaxial layers. Iso-intensity contours from the reciprocal space maps show very little broadening in ω which indicates less mosaicity in the samples. The ω–2θ direction shows almost no broadening implying that there is almost no strain in the material.