IMPORTANCE OF THE SURFACE ELECTRONIC-STRUCTURE IN HETEROEPITAXY

Thin Au and Pd films were deposited on a Nb(001) surface covered with a monolayer (ML) of the respective metal and on a S-terminated Nb. Alt hough these ML's have the same lateral periodicity as the substrate, t he films grown on them have a different structure. Films deposited on the metal-terminated Nb surface have a structure determined by the geo metric misfit between substrate and deposit (Au bcc, Pd hcp) while all films grown on the S-terminated Nb surface are fee with (111) orienta tion. Photoelectron spectroscopy shows that S changes the electron den sity of states at the surface in such a way that the bonding of the me tal is weakened, resulting in nonwetting.