Defects in (111) 3C-SiC layers grown at different temperatures by VLS and CVD on 6H-SiC substrates

In the present work homoepitaxial (111) 3C-SiC layers, grown by Chemical Vapour Deposition (CVD) on top of 3C-SiC seeds grown by the Vapour Liquid Solid (VLS) mechanism on Si-face on-axis (0001) 6H-SiC substrates, are investigated by means of Transmission Electron Microscopy (TEM). The CVD process was performed at constant C/Si ratio and the growth temperature was varied from 1450 degrees C to 1650 degrees C. The main defects in the VLS seeds which are directly nucleated on the interface with the 6H-SiC substrate are microtwins, dislocations and stacking faults (SFs). Within the CVD layers, the main defects appearing are also SFs together with multiple twin complexes which consist of two Sigma 3 and one Sigma 9 boundaries. Systematic analysis revealed that the multiple twin complexes disappear with increasing temperature while the trend for SF's is more difficult to follow. Some 3C to 6H polytypic transformation was found to occur at CVD growth temperature above 1550 degrees C.