Silicon carbide surface oxidation and SiO2/SiC interface formation investigated by soft X-ray synchrotron radiation
| Autor: | P. Soukiassian, F. Amy |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Radiation
Materials science Passivation Photoemission spectroscopy Analytical chemistry Oxide chemistry.chemical_element General Medicine Condensed Matter Physics Oxygen Atomic units Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials Overlayer chemistry.chemical_compound Crystallography chemistry Silicon carbide Physical and Theoretical Chemistry Carbon Spectroscopy Surface reconstruction |
| Zdroj: | Journal of Electron Spectroscopy and Related Phenomena. :783-788 |
| ISSN: | 0368-2048 |
| DOI: | 10.1016/j.elspec.2005.01.254 |
| Popis: | The most recent investigations into the atomic scale understanding of silicon carbide (SiC) surface oxidation and subsequent initial oxide/SiC interface formation are reviewed for the 6H and 4H hexagonal polytypes. These studies are conducted using advanced experimental techniques primarily based on core level photoemission spectroscopy using synchrotron radiation. The results indicate a very high reactivity to oxygen of the Si-rich 6H/4H–SiC(0 0 0 1) 3 × 3 surface reconstruction (≈3 orders of magnitude larger than for Si surfaces). Oxygen atom insertion is taking place below the surface close to the first carbon atomic plane, leaving the Si ad-atoms unaffected. By low temperature (500 °C) oxidation of a predeposited Si overlayer onto the 6H–SiC(0 0 0 1) 3 × 3 surface, a carbon-free SiO2 ultrathin film (≈10 A) could be grown, leading to the formation of an abrupt SiO2/6H–SiC interface. However, the two 6H and 4H polytypes have significantly different behaviors with larger amounts of oxide products having higher oxidation states for the 6H–SiC(0 0 0 1) 3 × 3 surface, while mixed oxides including carbon species (Si O C) are the dominant oxidation products for the 4H polytype surface. The oxidation rate is improved at increased surface temperatures. In all cases, the oxygen uptake remains significantly larger for the 6H polytype when compared to the 4H one. The very different behavior of the 6H and 4H polytypes seems to originate, at least in part, from the presence of two domains in the bulk for the 4H polytype (as evidenced by two bulk components in the Si 2p core level spectrum), which limits the oxygen insertion into the 4H–SiC lattice. These findings show that a “gentle” oxidation could be a promising approach to SiC surface passivation. |
| Databáze: | OpenAIRE |
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