AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS-ThP

Paper SS-ThP8
Control of Atomic Step Arrangements on a Patterned Si(111) Substrate Through Molecular-Beam Epitaxy

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: H. Omi, NTT, Basic Research Labs, Japan
Authors: H. Omi, NTT, Basic Research Labs, Japan
T. Ogino, NTT, Basic Research Labs, Japan
Correspondent: Click to Email
Atomic steps on a surface have great potential to act as templates for nanostructure formation. Therefore, control of step arrangement is critical for positioning these nanostructures on a wafer-scale. In our previous study,@footnote 1@ we have focussed on step motions on a patterned Si(111) surface during high temperature annealing and found that regular atomic step bands are formed on the surface. In this presentation, we show that atomic step arrangement can also be designed by step-flow growth on a patterned Si(111) surface using molecular-beam epitaxy. We used a Si(111) wafer, miscut by 1.5 ° to the direction, 7 ° rotated from the [1 1 -2] direction, on which periodic mesa and trench patterns were fabricated by standard Si process. These patterns are aligned along the direction, 7 ° rotated from the [1 1 -2]. The pattern sizes are 1 - 10 µm wide and 1 µm deep. By the introduction of such boundaries on the Si(111) surface, step-flow speed can be changed. This is because, concentration of adsorbed atoms on the restricted surface will be modulated by the presence of boundaries. In fact, we obtained particular step patterns related to the step-flow speed modulation. On a surface of 1 µm wide mesa, for instance, steps become curved and projected towards the [-1 -1 2] direction by high temperature annealing before the Si deposition. These steps evolve into arrowhead-like shape with increasing Si layer thickness. These step arrowheads point towards the [1 1 -2] direction at an arrow angle of 60 °, and therefore suggest that they are composed of [-1 -1 2] type steps. The above results demonstrate that the orientation of steps on a Si(111) surface can be regulated by introducing boundary conditions into the step-flow growth. The step-flow growth on a patterned substrate offers the possibility to design step arrangements on a wafer scale. @FootnoteText@ @footnote 1@ T. Ogino, H. Hibino, and Y. Homma, Appl. Surf. Sci. 117/118, 642 (1997).