Resonant photoexcitation of Si(001) measured with two-photon photoemissionspectroscopy - art. no. 125324

Photoexcitation processes of Si(001) are measured by means of two-photon ph otoemission (2PPE) spectroscopy. The 2PPE spectra obtained at different pho ton energies exhibit a sharp peak that is enhanced at 3.95 eV photon energy . The peak width is approximately 0.3 eV and the width of the resonance enh ancement is less than 0.35 eV. The photon energy dependence has revealed th at the peak arises from an occupied state at 0.46 eV below E-F, and is enha nced at resonance with an unoccupied state at 3.49 eV above E-F. The occupi ed and unoccupied states are assigned to the bulk bands on the basis of the light polarization dependence.