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Sulfur-induced c (4×4) reconstruction of the Si(001) surface studied by scanning tunneling microscopy

1993; American Physical Society; Volume: 47; Issue: 23 Linguagem: Inglês

10.1103/physrevb.47.15950

1095-3795

Philip Moriarty, Ludger Koenders, G. Hughes,

Surface and Thin Film Phenomena

Scanning tunneling microscopy and low-energy electron diffraction have been used to study the adsorption and subsequent thermal desorption of molecular sulfur from the Si(001) surface. Room-temperature adsorption of sulfur resulted in the formation of an overlayer, displaying a high density of vacancies or defects, with the underlying Si(001) surface retaining the (2\ifmmode\times\else\texttimes\fi{}1) reconstruction. Annealing this surface to 325 \ifmmode^\circ\else\textdegree\fi{}C leads to the desorption of the sulfur overlayer and the appearance of coexisting c(4\ifmmode\times\else\texttimes\fi{}4) and (2\ifmmode\times\else\texttimes\fi{}1) surface reconstructions. Our data suggest that the c(4\ifmmode\times\else\texttimes\fi{}4) reconstruction is an adsorbate-induced structure in which the sulfur creates defects during the desorption process. High-resolution filled- and empty-state images of the c(4\ifmmode\times\else\texttimes\fi{}4) surface lead us to propose a missing-dimer defect model for this reconstruction.