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Direct Dimer-by-Dimer Identification of Clean and Monohydride Dimers on the Si(001) Surface by Scanning Tunneling Microscopy
Interim rept. 1 Jun 1993-31 May 1994
WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY
Pagination or Media Count:
Atomic resolution images of clean Si001-2x1 and the mono-hydride phase, Si001-2xlH were investigated using scanning tunneling microscopy at various sample-tip bias voltages. At a sample-tip bias of -1.9 V, each dimer of the monohydride phase show two protrusions 3.3 A apart separated by a minimum 0. 11 A deep for a sample bias of -1.9 Volt, while clean dimers show a single protrusion per unit cell. Monohydride dimers appear lower than clean dimers, with apparent height differences ranging from 1.9 A at -1.6 V to 0.65 A at -3.0 V sample bias. An analysis of the apparent height and spatial distribution of tunneling current within each dimer can be used to unambiguously discriminate between clean dimers, monohydride dimers, and vacancy defects. This methodology is applied to study the distribution using disilane, revealing segregation of the monohydride into nearly isotropic islands.
APPROVED FOR PUBLIC RELEASE