CrSi2 formation and reduction of Cr2O3, during annealing of an oxidized Cr overlayer on Si(111)
1986; Elsevier BV; Volume: 178; Issue: 1-3 Linguagem: Inglês
10.1016/0039-6028(86)90277-3
ISSN1879-2758
AutoresP. Wetzel, C. Pirri, J.C. Peruchetti, D. Bolmont, G. Gewinner,
Tópico(s)Electron and X-Ray Spectroscopy Techniques
ResumoA 250 Å thick Cr layer evaporated on Si(111) in ultrahigh-vacuum conditions and subsequently oxidized by exposition to molecular oxygen in order to form a Cr2O3 overlayer of ∼10 Å, is studied as a function of annealing in the range 300–800°C by X-ray and ultraviolet photoemission spectroscopy. In the early stages of annealing Si diffusion through the Cr film is observed. These Si atoms are embedded in a metal-rich environment and react readily with the superficial Cr2O3 compound to form a film of SiO2. Upon further annealing it is found that the CrSi2 growth front reaches the depth probed in our experiments (∼ 5–20 Å). Yet, the results clearly demonstrate that even after prolonged annealing at 500°C complete decomposition of the Cr2O3 film does not occur. Apparently, the silicon dioxide already formed acts like a diffusion barrier, preventing further silicon species to reach the remainder of the chromium oxide.
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