A comparative study of high-quality C-face and Si-face 3C-SiC(111) grown on off-oriented 4H-SiC substrates

Although cubic silicon carbide (3C-SiC) has been regarded as a promising material for optoelectronic and power-device applications, the growth of high-quality 3C-SiC remains as a great challenge for decades. In particular, C-face 3C-SiC exhibits material superiorities for high electron mobility transistors compared to the Si-face 3C-SiC. However, the growth of C-face 3C-SiC is even more challenging and has not been explored yet. In this work, we comparatively investigate growth of high-quality C-face and Si-face 3C-SiC(111) on off-oriented 4H-SiC substrates by the sublimation epitaxy. The C-face sample exhibits a smoother surface with step height of one-unit cell while the surface of the Si-face sample exhibits steps twice as high as on the C-face due to step-bunching. High-resolution XRD and low temperature photoluminescence measurements show that C-face 3C-SiC can reach the same high crystalline quality as the Si-face 3C-SiC. Furthermore, cross-section studies of the C- and Si-face 3C-SiC demonstrate that in both cases an initial homoepitaxial 4H-SiC layer followed by a polytype-transition layer are formed prior to the formation and lateral expansion of 3C-SiC layer. However, the transition layer in the C-face sample is extending along the step-flow direction less than that on the Si-face sample, giving rise to a more fairly consistent crystalline quality 3C-SiC epilayer over the whole sample compared to the Si-face 3C-SiC where more defects appeared on the surface at the edge. This facilitates the lateral enlargement of 3C-SiC growth on hexagonal SiC substrates.