SINGLE AND DOUBLE-LAYER GROWTH MECHANISMS INDUCED BY QUANTUM SIZE EFFECTS IN PB FILMS DEPOSITED ON CU(111)

The specular intensity of nearly mono-energetic helium atom beams (E(i) = 7-20 meV) has been measured during epitaxial deposition of Pb films on a clean and well annealed Cu(111) surface. A complicated modulated structure was found indicating an alternation between single and double layer growth mechanisms. This is also supported by kinematic studies and step height determinations performed at various points in the growth curve. A quantum size effect in the overlayer electronic states is shown to influence the growth mechanism. The frequency of alternation between single and double layer growth, with increasing thicknesses, corresponds to that frequency predicted by the fit or misfit of Pb Fermi-energy standing waves in the overlayers.