Nucleation and growth of an epitaxial monolayer of Cd on Ge(111): A simultaneous RHEED–molecular‐beam study

摘要

The nucleation and growth of an epitaxial monolayer of Cd on Ge(111) was studied by simultaneously employing RHEED and the mass spectrometric molecular beam (MSMB) technique. The MSMB spectra are discussed in terms of the atomistic rate theory of nucleation and the correlation between structures and spectra is presented. The results suggest that a convention of nucleation rate theory, that growing clusters act as monomer capture centers which increase in capture efficiency with time, does not hold at submonolayer coverages for this system. A model where capture efficiency decreases with cluster size is considered and from this model an estimate of the heat of adsorption and the activation energy for diffusion of monomers is obtained. Independent of the model we find that the nucleation process precedes the epitaxial alignment of clusters.