TIME EVOLUTION OF A METALLIC ULTRA-THIN FILM BY SURFACE ELECTRO-MIGRATION

The morphological change of a thin film patch caused by surface electr o-migration is investigated, with the use of a computer simulation bas ed on the lattice gas model. In the Stranski-Krastanov mode the contri bution of constituent atoms of an intermediate layer is also considere d in the mass transport, in addition to adatoms on the intermediate la yer. Three kinds of binding energies are introduced among atoms; betwe en the intermediate layer and the substrate, between an adatom and the intermediate layer and between deposited atoms. The numerical results can explain well the difference observed in the behaviour for Ag/Si(1 11) and Ga/Si(111), and the criterion between the two kinds of behavio ur is clarified. For Ga/Si(111) the effect of desorption is also consi dered. The surface electron-migration in the Volmer-Weber mode is stud ied for the first time, and the possibility of the diffusion motion of islands of deposited atoms directly on the substrate is found.