Direct Observation of a New Growth Mode: Subsurface Island Growth of Cu on Pb(111)

Abstract

Atomically resolved scanning tunneling microscopy on Cu/Pb(111) reveals a new growth mode, contrary to the Volmer-Weber mode expected from the significantly lower surface energy of Pb. (111)-oriented Cu islands with a thickness of 3--11 layers are immersed in the Pb substrate and covered by a single close-packed Pb layer. This subsurface growth mode occurring at room temperature can be explained by simple thermodynamic considerations.