C. Senemaud et al., ELECTRONIC-STRUCTURE OF SILICON-NITRIDE STUDIED BY BOTH SOFT-X-RAY SPECTROSCOPY AND PHOTOELECTRON-SPECTROSCOPY, Journal of applied physics, 74(8), 1993, pp. 5042-5046
The valence and conduction band states of crystalline silicon nitride
alpha-Si3N4 have been studied by using two complementary experimental
methods. The total valence band distribution has been analyzed by x-ra
y induced photoelectron spectroscopy. The Si 3p valence states and the
Si p conduction states have been probed selectively by x-ray emission
and absorption spectroscopies, respectively. The experimental curves
have been compared in the same energy scale referred to the Fermi leve
l. Our results show clearly that the N 2ppi states of Si3N4 are locate
d at the top of the valence band while Si 3p states, mixed to N 2p sta
tes and, respectively, to N 2s states are located at about E(F) - 8.4
eV and E(F) - 19.6 eV. Our experimental results are in very good agree
ment with theoretical simulations of the spectra made from recent dens
ity of states calculations by Robertson [Philos. Mag. B 63, 47 (1991)]
in a tight binding approach.