Clean surface and oxidation behavior of vanadium carbide, VC0.75(100)

The clean single-crystal VC 0.75 (100) surface, its oxidation, and the stability of the resulting oxide were examined with electron spectroscopy (AES, XPS and UPS), electron diffraction (low-energy and reflection high energy electron diffraction) and atomic force microscopy (AFM). The clean VC 0.75 surface exhibits carbon vacancy-related features in valence band spectroscopy data. This surface was exposed to O 2 at 500 °C for up to 10 000 Langmuirs. The oxidation leads to the formation of vanadium oxide, VO x (100), crystallites on the VC 0.75 (100) substrate. The AFM images indicate that oxide crystallites grow with an elongated shape along type directions. When heated above 1000 °C, the oxide is unstable and a clean VC 0.75 (100) surface is produced.