Electronic structures of silicon monoxide film probed by X-ray absorption spectroscopy

Baba, Yuji  ; Sekiguchi, Tetsuhiro  ; Shimoyama, Iwao   ; Hirao, Norie

Electronic structures of thin films of silicon monoxides (SiO) deposited on a solid surface have been in-situ investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS). For thin films with less than monolayer on highly oriented pyrolytic graphite (HOPG), it was elucidated that the stable divalent silicon surely exists in the deposited SiO layer. For the Si K-edge XAFS spectrum of the SiO thin film, the energy of the core-to-valence resonance peak is located between those of the elemental silicon (Si) and SiO (Si). The polarization dependence of the Si K-edge XAFS spectra revealed that the SiO molecules are well-ordered and almost perpendicularly oriented on HOPG surface. The obtained well-ordered SiO films with divalent silicon will become an excellent starting material for the synthesis of low-dimensional SiO films.