Growth Mechanism of 3C-SiC Heteroepitaxial Layers on α-SiC by VLS

We report on the heteroepitaxial growth of 3C-SiC layers by Vapor-Liquid-Solid (VLS) mechanism on Si face 6H-SiC substrates, on-axis and 3.5 degrees off. The Si-Ge melts, which Si content was varied from 10 to 50 at%, were fed by 3 sccm of propane. The growth temperature was varied from 1200 to 1600 degrees C. It was found that 3C-SiC layers (either twinned or twinned free) form at low temperature while homoepitaxy is achieved at high temperature. The proposed growth mechanism involves the initial formation of 3C islands during the heating ramp (below 1200 degrees C and the dissolution of these islands when temperature increases. Geometrical aspects, such as the step density at the surface and the vertical component of the growth, are also considered to explain the difference observed between the on and off axis substrates.