XPS spectra of chromium monosilicides and disilicides obtained by in situ fractured clean surfaces

X-ray photoelectron spectroscopy spectra of chromium monosilicide (CrSi) and disilicide (CrSi2) were collected from a clean surface prepared by fracturing the bulk silicide compound in a spectrometer under ultrahigh vacuum; the analytical procedure for the phase identification of the Cr-Si system was examined. A negligible binding energy shift was observed in the Cr 2p(3/2)level between elemental Cr and CrSi2, whereas the energy of CrSi was 0.2 eV lower than that of Cr and CrSi2. The satellite peak in the Cr 2p spectra originating from the plasmon-loss phenomena was found only for CrSi and CrSi2. The binding energy of Si 2p shifted, reflecting the silicide phases; the energy of CrSi(2)and CrSi was 0.3 eV higher and lower, respectively, than that of elemental Si. Although a slight difference in the spectral shape was observed in the valence band region, the phase identification was considered unreliable. However, the energy shifts of Si 2p and the presence of the plasmon-loss peak in the Cr 2p spectra provide important insights into the phase identification of the Cr-Si system.