AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP5
Oxygen Reactivity of Clean and Au-induced High-Index Si Surfaces

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: J.L. Skrobiszewski, Virginia Commonwealth University
Authors: J.C. Moore, Virginia Commonwealth University
J.L. Skrobiszewski, Virginia Commonwealth University
A.A. Baski, Virginia Commonwealth University
Correspondent: Click to Email
We have studied the oxygen reactivity of the clean high-index Si(5 5 12) surface, as well as nearby Au-induced facet planes. The (5 5 12) surface is oriented approximately midway between the (001) and (111) planes and forms a single-domain, row-like reconstruction. When submonolayer coverages of Au are deposited and annealed on Si(5 5 12), the surface undergoes significant restructuring to form a variety of nearby facet planes. In this work, we use scanning tunneling microscopy to investigate the O@sub 2@ reactivity of these various surfaces for a range of temperatures (600 to 800 °C), pressures ( 10@super -7@ to 10@super -6@ Torr), and exposures (50 to 200 Langmuirs). At lower temperatures (<700 °C), O@sub 2@ exposure of the clean (5 5 12) surface results in disordered oxide growth, similar to that previously observed for the low-index Si surfaces. At higher temperatures (>700 °C), etching is observed via step retraction and subsequent pinning by small islands, presumably due to oxide growth. The density of these islands decreases at higher temperatures (800 °C), indicating that oxide etching dominates in this temperature regime. With regard to the Au:Si(5 5 12) system, for oxygen exposures of ~100 L and moderate temperatures (700 to 750 °C), oxide island formation is seen on the lower Au coverage (337) facets, but no etching or oxidation is observed on higher coverage facets such as (5 5 11). This behavior indicates enhanced stability of the higher coverage Au-induced surfaces, which is consistent with the passivating nature of this adsorbate.