Growth and Microstructure of Epitaxial Ti₃SiC₂ Contact Layers on SiC

Abstract

Growth and microstructure of ternary Ti₃SiC₂ compound layers on 4H-SiC, which play am important role in formation of TiAl-based ohmic contacts to p-type SiC, were investigated in this study. The Ti₃SiC₂ layer was fabricated by deposition of Ti/Al contacts (where a slash “/” indicates the deposition sequence) on the 4H-SiC(0001) substrate and subsequent rapid thermal anneal at 1000°C in ultra high vacuum. After annealing, reaction products and microstructure of the Ti₃SiC₂ layer were investigated by X ray diffraction analysis and transmission electron microscopy observations in order to understand the growth processes of the Ti₃SiC₂ layer and determination of the Ti₃SiC₂/4H-SiC interface structure. The Ti₃SiC₂ layers with hexagonal plate shape were observed to grow epitaxially on the SiC(0001) surface by anisotropic lateral growth process. The interface was found to have a hetero-epitaxial orientation relationship of (0001)_TSC||(0001)_S and [0\\bar110]_TSC||[0\\bar110]_S where TSC and S represent Ti₃SiC₂ and 4H-SiC, respectively, and have well-defined ledge-terrace structures with low density of misfit dislocations due to an extremely low lattice mismatch of 0.4% between Ti₃SiC₂ and 4H-SiC.