Electron energy-loss spectroscopy study of the electronic structure of Li- and V-doped beta-rhombohedral boron

Electron energy-loss spectra of Li- and V-doped beta-rhombohedral boron (beta-r-B) were measured from perfect crystalline areas of 180 nm in diameter. The onset of spectra of Li-doped beta-r-B was observed at about 1.5 eV, but that of V-doped beta-r-B was not clearly observed. The volume plasmon peaks of Li- and V-doped beta-r-B were observed at 23.1 and 23.6 eV, respectively. The energy onset of the B K-shell excitation spectra of V-doped beta-r-B was lower than that of beta-r-B by 0.9 eV. The lower onset indicates a decrease of the band gap energy with V-doping. Such a decrease of the energy onset was not observed in Li-doped beta-r-R. (C) 1997 Academic Press.