A transmission electron microscopy investigation of SiC films grown on SiCsubstrates by solid-source molecular beam epitaxy

The relationship between the defect microstructure of SiC films grown by so lid-source molecular-beam epitaxy on 4H and 6H-SiC substrates and their gro wth conditions, for substrate temperatures ranging between 950 and 1300 deg rees C, has been investigated by a combination of transmission electron mic roscopy and atomic force microscopy. The results demonstrate that the forma tion of defective cubic films is generally found to occur at temperatures b elow 1000 degrees C. At temperatures above 1000 degrees C our investigation s prove that simultaneous supply of C and Si in the step-flow,growth mode o n vicinal 4H and 6H substrate surfaces results in defect-free hexagonal SiC layers, and defect-free cubic SiC can be grown by the alternating depositi on technique. The controlled overgrowth of hexagonal on top of cubic layers is demonstrated for thin layer thicknesses.