We present a novel “electronic growth” model for metallic thin films on semiconductor substrates. Depending on the competition between the effects of quantum confinement, charge spilling, and interface-induced Friedel oscillations, different types of film stability are defined, as characterized by the existence of critical/magic thicknesses for smooth growth. In particular, smooth growth can be achieved only above a few monolayers for noble metals, and only for the first layer for alkali metals.

• Received 3 November 1997

DOI:https://doi.org/10.1103/PhysRevLett.80.5381