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Split-off dimer defects on the Si(001)2x1 surface

Schofield, SR; Curson, NJ; O'Brien, JL; Simmons, MY; Clark, RG; Marks, NA; ... Hawley, ME; + view all (2004) Split-off dimer defects on the Si(001)2x1 surface. PHYS REV B , 69 (8) , Article 085312. 10.1103/PhysRevB.69.085312.

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Abstract

Dimer vacancy (DV) defect complexes in the Si(001)2x1 surface are investigated using high-resolution scanning-tunneling microscopy and first-principles calculations. We find that under low-bias filled-state tunneling conditions, isolated "split-off" dimers in these defect complexes are imaged as pairs of protrusions, while the surrounding Si surface dimers appear as the usual "bean-shaped" protrusions. We attribute this to the formation of pi-bonds between the two atoms of the split-off dimer and second-layer atoms, and present charge density plots to support this assignment. We observe a local brightness enhancement due to strain for different DV complexes and provide the first experimental confirmation of an earlier prediction that the 1+2-DV induces less surface strain than other DV complexes. Finally, we present a previously unreported triangular shaped split-off dimer defect complex that exists at S-B-type step edges, and propose a structure for this defect involving a bound Si monomer.

Type:Article
Title:Split-off dimer defects on the Si(001)2x1 surface
DOI:10.1103/PhysRevB.69.085312
Keywords:SCANNING-TUNNELING-MICROSCOPY, ELECTRONIC-STRUCTURE, SI(100) SURFACE, LOW-TEMPERATURE, DENSITY, VACANCIES, SILICON, STEPS, ROOM
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology

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