Scanning tunneling microscopy study of low-temperature epitaxial growth of silicon on sI(111 )-(7×7)

Scanning tunneling microscopy is used to investigate nucleation and growth phenomena in the molecular-beam epitaxial (MBE) growth of silicon on Si(111)-(7×7) from the submonolayer range up to a few monolayers. At room temperature small amorphous clusters form which grow in locally ordered arrays on the (7×7) lattice. Deposition at a higher substrate temperature produces triangular islands of epitaxial silicon which have preferred step propagation in the [112] direction. Preferred nucleation of Si islands is found to occur along boundaries between (7×7) superstructure translational domains of the substrate. The preferred nucleation which arises from defects in the epilayer accounts for the formation of a second epitaxial layer long before the first layer is completed. A variety of metastable reconstructions which differ from (7×7) are also found in the epitaxial islands and are discussed. © 1989, American Vacuum Society. All rights reserved.