UHV-SEM study of the nucleation and growth of Ag/W(110)

Abstract

The nucleation and growth of Ag on W(110) single crystals has been studied by ultra-high vacuum SEM, AES and electron backscattering techniques. The system is confirmed to grow in the Stranski-Krastanov growth mode with 2 stable monolayers (ML) in the intermediate layer. Island density measurements are reported in the temperature range 473 < T < 823 K at a deposition rate R = 0.3 ML min −1, and at T = 573 and 773 K for 0.03 < R < 0.8 ML min −1. These results are interpreted in terms of nucleation theory. They are consistent with critical nucleus sizes in the range 7–10 atoms, and binding energies of small, two-dimensional Ag clusters which are less than expected on the simplest pair-bonding arguments. More qualitative observations on defect-induced nucleation and the shape of the growing islands are also reported.