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7Kakiuchi, Takuhiro*; Anai, Ryota*; Saiki, Taiju*; Tsuda, Yasutaka; Yoshigoe, Akitaka
Journal of Physical Chemistry C, 128(31), p.13052 - 13063, 2024/08
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)0xidation at the interface and the surface of Si(111) substrate with thin Hf films were studied using synchrotron radiation photoelectron spectroscopy in conjunction with supersonic oxygen molecular beams (SOMB). An Hf/Si(111) with a coverage of 0.5 monolayer (ML) included HfSi and HfSi
. Following exposures to thermal oxygen molecules with a translational energy (Et) of 0.03 eV, HfSi was oxidized into Hf
valence. Following SOMB irradiation with Et of 0.39 eV, the other HfSi could be oxidized into the Hf
. Following the thermal O
exposures, the metallic Hf was nonlocally oxidized to HfO via trapping-mediated dissociative adsorption. Meanwhile, the segregated Si atoms were oxidized by SOMB irradiation with 2.2 eV and SiO was generated on the surface.
Kakiuchi, Takuhiro*; Anai, Ryota*; Saiki, Taiju*; Tsuda, Yasutaka; Yoshigoe, Akitaka
no journal, ,
Initial oxidation mechanism of hafnium adsorbed Si(111)-77 [Hf-Si(111), the thickness of Hf:0.5 monolayer] was studied by synchrotron radiation X-ray photoelectron spectroscopy. The individual Hf atoms were associated with the back bonds of Si rest atoms or Si adatoms on Si(111)-77, and the Hf monosilicide HfSi) unit was formed on the outermost surface. Following the HfSi units immediately reacted with the thermal O molecules [translational energy (Et=0.03eV], Hf silicates (Hf-O-Si) were produced. In addition, some dissociated O atoms were inserted between the adsorbed Hf atoms. As a result, Hf sub-oxides/silicates up to 3+ states were formed. When a non-equilibrium condition was induced by irradiation of the supersonic O molecular beam of Et = 0.39 eV, the Hf4+ state was confirmed along with and the oxidation of Si bulk. This indicates that there is an activation energy to oxidize the Hf-Si bonds of the bulk side.
