Diffusion of gold in 3C-SiC epitaxially grown on Si Structural characterization

The structural characteristics of gold/3C-SiC contacts, subjected to a long annealing at 500 °C for 500 h for aging investigation, were studied by transmission electron microscopy. After the aging test about 50% of the gold which was deposited on the SiC surface was diffused through the 2.5 μm thick 3C-SiC to the SiC/Si interface forming an almost continuous gold film resulting in a SiC/Au/Si structure. The intermediate gold film is in perfect epitaxial relation to the 3C-SiC overgrown and the Si substrate, in spite of the 25% misfit between the Au and Si. Moiré fringes produced by the interference of the Au and Si lattices reveal that the two lattices are perfectly relaxed. No linear or planar defects were observed in the gold film. No Au precipitates were observed inside the 3C-SiC overgrown or in the Si-substrate. A mechanism responsible for the formation of the intermediate gold film in the SiC/Si interface is proposed.