Abstract
Ordered (2×2) and [formula omitted] Pt–Sn(111) surface alloys were oxidized by [formula omitted] exposure at 400 K under ultrahigh vacuum conditions. The evolution of the surface morphology with annealing temperature was characterized by using low energy electron diffraction (LEED), scanning tunneling microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy. Both oxidized surface alloys form a [formula omitted] overlayer that wets the substrate. However, the [formula omitted] film does not completely cover the surface for the oxidized (2×2) surface alloy. For the oxidized [formula omitted] surface alloy, an ordered (4×4) LEED pattern is formed upon flash annealing above 900 K. The formation of this ordered [formula omitted] adlayer coincides with Sn segregation from the bulk to the interface region. A model for the (4×4) structure is discussed. The [formula omitted] overlayer formed by oxidation of the (2×2) surface alloy is significantly less thermally stable than the oxidized [formula omitted] surface alloy. Exothermic alloying of Sn with Pt may facilitate the decomposition of the oxide overlayers. Differences in the amount of subsurface tin and its segregation to the surface is proposed to explain the thermal stabilities of the oxide layers. The incompleteness of the [formula omitted] overlayer and less subsurface tin for the oxidized (2×2) surface alloy is proposed to explain its significant lower thermal stability.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1953-1958 |
| Number of pages | 6 |
| Journal | Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films |
| Volume | 19 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jul 2001 |
| Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
Keywords
- Pt
- Sn