Binding and diffusion of a Si adatom around the type A step on Si(001) {ital c}(4{times}2)
- Materials Research Laboratory and Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States)
- Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701 (United States)
The results of a simulation are described, using a density functional method, of the diffusion of adatoms on a flat Si(001){ital c}(4{times}2) surface and around one type of surface step (the {ital S}{sub {ital A}} step). These indicate that there is a moderate additional energy barrier (0.2{plus_minus}0.1 eV) to cross the {ital S}{sub {ital A}} step as compared to the energy for diffusion on a flat surface. The dimer-top lattice site on the lower terrace adjacent to the step edge is stabilized (by 0.15{plus_minus}0.1 eV) with respect to the flat surface result although the most stable binding sites near the step are unaffected. This behavior can be understood based on the disruption of dimer tilt near the step. The results suggest that adatoms are more likely to stop on lattice sites at the {ital S}{sub {ital A}} step edge than on lattice sites on the open surface. This may affect the relative dimer formation rate near the step with respect to the behavior on the flat surface even in the absence of a clear change in binding energy. The effect of the {ital S}{sub {ital A}} step terrace edge on adatom behavior is very short ranged and weak. This is consistent with the relatively small strain field and lack of change in dangling bond density associated with the step edge.
- Research Organization:
- University of Illinois
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 29242
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 15 Vol. 66; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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