AVS 45th International Symposium
    Nanometer-scale Science and Technology Division Tuesday Sessions
       Session NS-TuA

Paper NS-TuA2
Formation and Characterization of Metal Atom Nanostructures on Si(112) Facet Surfaces

Tuesday, November 3, 1998, 2:20 pm, Room 321/322/323

Session: Quantum Wires and Quantum Dots
Presenter: S.M. Prokes, Naval Research Laboratory
Authors: S.M. Prokes, Naval Research Laboratory
O.J. Glembocki, Naval Research Laboratory
Correspondent: Click to Email
Facet semiconductor surfaces have been suggested for use as templates in the formation of ordered dots and lines. A bulk-terminated Si(112) surface is of particular interest since it consists of distinguishable (111) terraces and (001) steps which can serve as a template for the formation of well-ordered nanostructures, such as metallic wires or dots, with the aim of producing electron gratings and magnetic nanostructures. We have studied the formation of Ga, Al and Sc nanostructures on facet Si(112) surfaces, which were investigated using LEED, Auger spectroscopy and Reflectance Difference Anisotropy (RDA). Although the clean Si(112) surface exhibits (1x2) reconstruction, we found that the deposition of Ga or Al above 300°C removes this reconstruction and leads to a periodic stepped structure of alternating (111) terraces and (001) steps. Ga or Al chains then form by a self-limiting process, which we can track from the rapid change of the (2x1) Si(112) reconstruction under sub-critical coverage, to chain formation leading to a 5x1 reconstruction followed by a 6x1 reconstruction, using RDA. Furthermore, AES and RDA results show the replacement of Ga atoms by Al atoms at the step edges during sequential deposition of Ga and Al, indicating a stronger Al-Si bond. Using RDA, we have also observed that depositions at lower temperatures can lead to the formation of Ga metallic wires on the Si(111) terraces. For Sc, we find that its higher surface energy precludes the formation of wires but leads to the formation of nanometer-size Sc islands, which may exhibit enhanced magnetic moments. Using Monte Carlo techniques to model the time evolution of the deposition at various temperatures, we are also able to extract highly accurate values for the surface kinetic parameters involved in the formation of these nanostructures.