Scanning tunneling microscopy and high-resolution low-energy electron diffraction techniques were used to determine the characteristics of the 2-dimensional Si island distribution on defect-free and imperfect Si(111) surfaces in real space and reciprocal space. The surface power spectra of scanning tunnelling microscopy and modeling of diffraction profiles give consistent island separation. Unlike the sub-monolayer nucleation of Si islands on a defect-free Si(111) surface, it was shown that the island size distribution of Si, nucleated on a Si(111) surface having a high density of vacancy defects, did not exhibit a preferred characteristic island size. The process was interpreted as defect-induced nucleation with the critical island size equal to zero, for which there was no free energy barrier for nucleation. The results were qualitatively consistent with recent computer simulations, and were compared with other recent experimental work.

Vacancy-Enhanced Sub-Monolayer Nucleation of Si on Si(111). J.B.Wedding, G.C.Wang, T.M.Lu: Surface Science, 2002, 504, 28-36