The Schottky barrier of a heavily doped Si layer covered with a metal film is investigated using conduction electron spin resonance, which is utilized in situ in UHV to continuously monitor the metal overlayer development from a fractional monolayer through multiple layers. Measured increases in linewidth are compared with calculations based on a kinetic theory. For Al and Ag, the data can be explained both by flat-surface and island models, even though for Al only a flat-surface model with smooth surfaces is compatible with the experiments. In contrast, for Cu and Al-Cu bilayers, the data unambiguously favor the rough-surface island model.

DOI:https://doi.org/10.1103/PhysRevB.55.13745