Accession Number:

ADA265269

Title:

Adsorption and Dissociation of Disilane on Si(001) Studied by STM

Descriptive Note:

Interim rept. 1 Jun 1992-31 May 1993

Corporate Author:

WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY

Report Date:

1993-05-01

Pagination or Media Count:

44.0

Abstract:

The surface-adsorbed fragments resulting from the room-temperature adsorption and dissociation of disilane Si2H6 on Si001 are observed and identified using Scanning Tunneling Microscopy STM. The predominant fragments are H and SiH2, which are identified by the symmetries of their binding sites on the surface. H atoms often bind near single or double dimer vacancy defects, while SiH2 tends to bind near C-type defects. We find that adsorbed H atoms induce buckling of the dimer rows on the Si001 surface, while SiH2 groups do not. This difference is ascribed to differences in the electronic structure of the two surface-bound species. No systematic correlation between the positions of-the H atom and SiH2 groups is evident, which indicates that the fragments of a single disilane molecule are not localized in a small region. This fact suggests that at least some of the molecular fragments from disilane dissociation are mobile on the Si001 surface at room temperature. Further decomposition of the SiH2 fragments can be induced by annealing, which produces surface structures similar to those seen in molecular-beam epitaxial growth of silicon small asymmetric islands form with low disilane coverages, whereas higher coverages give multilayer island growth.

Subject Categories:

  • Physical Chemistry
  • Crystallography
  • Atomic and Molecular Physics and Spectroscopy
  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE