Solid state dewetting of a metal –semiconductor bi-layers deposited onto c-Si substrate

A bi-layers stack consisting of a semiconductor thin film of a varied thickness and a very thin Pd layer (SiC/Pd/c-Si).was deposited onto c-Si by e-beam evaporation at room temperature. The multi-layers structure was subjected to a thermal annealing process at near eutectic temperature of the Si – Pd phase. It is noticed, through top view SEM and cross-section STEM analyses, that the sandwiched Pd metal layer dewets from the interface with the c-Si substrate in well dispersed nanoparticles and it diffuses inward onto the top few monolayers of the substrate; at times it permeates shallowly through the SiC semiconductor top layer. The size distribution of the nanoparticles was found to be closely linked to the thickness of the top semiconductor layer. On the other hand, the top SiC layer was found to form islands protruding above the surface, when the film was very thin. When thicker, the semiconductor SiC layer retained its integrity and remained unaffected. An optical model of the resulting metal-dielectric mixed layer is proposed.