Interfactant-mediated quasi-Frank-van der Merwe growth of Pb on Si(111)

The influence of interfactants (Au, Ag) on the growth of Pb on Si(111) is studied by low-energy electron microscopy in the temperature range from 260 K to 460 K. On the Si(111)-(7 × 7) surface Pb grows in the Stranski-Krastanov mode, on the Si(111)-(√3 × √3)R30°-Au and on the Si(111)-(6 × 6)-Au surface in the quasi-Frank-van der Merwe (layer-by-layer) mode. On the Si(111)-(√3 × √3)R30°-Ag surface the growth mode changes from layer-by-layer below 300 K to the Stranski-Krastanov mode above 300 K. The temperature dependence of the growth cannot be explained by thermodynamics but is governed by kinetics. The analysis of the maximum island density in terms of the atomistic nucleation theory gives acceptable values for nucleus size and energies only in the layer-by-layer growth regime. In the Stranski-Krastanov growth regime abnormal values are obtained that are attributed to high cluster mobility on the initial two-dimensional layer. The conditions leading to quasi-Frank-van der Merwe growth are discussed.