Accounting for anomalous oxidation states of silicon at the Si/SiO₂ interface

Abstract

The early oxidation stages of hydrogen-terminated single-crystalline Si(100) exposed to a diluted N 2 /N 2 O atmosphere at 850• C for different durations have been studied by XPS, following the evolution of the Si 2p signal. Evidence is given that the usual analysis, in terms of five pairs of peaks attributed to silicon in oxidation states from 0 to +4, does not account for the observed Si 2p signal. The spectrum is accurately reproduced only by assuming the existence of silicon in bonding configurations different from those usually assumed to occur at the Si/SiO 2 interface.

Quantitative XPS analysis of hydrosilated 1-alkene and 1-alkyne at terraced, dihydrogen-terminated, 1 × 1 (100) silicon

“…32 Rather, the Si 2p signal contained features (referred to as Si ý or Si 2ý ) at a binding energy higher than that of elemental silicon Si 0 by 0.3 0.6 eV. 30 The amount of adventitious carbon, evaluated from the survey spectra (not shown), on the hypothesis that it is mainly formed by methylene units, was found to be 1.5 2.0 ð 10 14 CH 2 cm 2 (the protocol adopted to extract this amount from raw spectra will be discussed later).…”

“…Operated with a monochromatized beam (photon energy h D 1486.6 eV) and a pass energy of 2.95 eV for all elements, the apparatus had an energy resolution of about 0.2 eV. 30 Spectra obtained with pass energies different from 2.95 eV will be mentioned explicitly. The energy was calibrated by centering the maximum of the Si 2p 3/2 peak on 99.000 eV.…”

Hydrosilation of 1-alkyne at nearly flat, terraced, homogeneously hydrogen-terminated silicon (100) surfaces

“…The distribution of silicon over its oxidation states in the sampled region may be determined using the decomposition method proposed by Himpsel et al, 29 corrected for features Si ý (shifted by about C0.3 eV from that of elemental silicon and attributed either to hydrogen-terminated unreacted silicon or to elemental silicon with oxygen as the secondnearest neighbour) 25 and Si C (shifted by about C0.4 eV and attributed to otherwise elemental silicon bonded to one carbon atom only). 30 The disappearance of the silicon signal as  is progressively reduced from 75°to 1°is a clear indication of the fact that the silicon is completely covered by a carbonaceous film.…”

“…Operated with a monochromatized beam photon energy D 1486.6 eV and a pass energy of 2.95 eV for all elements, the spectrometer had an energy resolution of ¾0.2 eV. 25 …”

XPS, AFM, ATR and TPD evidence for terraced, dihydrogen terminated, 1×1 (100) silicon

“…The XPS spectra were determined at different take-off angles using a PHI ESCA/SAM 5600 Multitechnique spectrometer with a monochromatized x-ray beam, operated in conditions which allow an energy resolution better than 0.2 eV. 14 The AFM measurements were carried out in the tapping mode with a Digital Instruments Multimode apparatus for samples (a), (b) and (c) or with an NT-MTD apparatus for sample (d). The ATR-IRAS measurements were carried out using a Harrick GATR germanium single reflection ATR accessory.…”