Study on the growth of heteroepitaxial cubic silicon carbide layers in atmospheric-pressure H2-based plasma

The heteroepitaxial growths of cubic silicon carbide (3C-SiC) layers on Si(001) substrates are studied at a temperature of 800 degrees C in atmospheric-pressure (AP) plasma excited by a 150 MHz, very high-frequency (VHF) power using a porous carbon electrode. The effect of a very large C/Si ratio (-400) of the source molecules on the improvement of crystallinity of the resultant SiC layer is mainly investigated. For this purpose, we utilize the chemical transport of Si induced by AP H2/CH4 plasma instead of using SiH4 as the Si source. The layer crystallinity is characterized using reflection high-energy electron diffraction, transmission electron microscopy and infrared absorption spectroscopy. The results show that the SiC layer exhibits the (001) 3C-SiC growth aligned to the Si matrix epitaxially. Although the SiC layer contains a high density of defects originating presumably from anti-phase boundaries and twin boundaries, the layer crystallinity has been considerably improved in comparison with that of the layer grown with C/Si = 10. It is also demonstrated that the moderate dilution of H2 with He leads to a further improvement of the layer crystallinity.