ATOMIC, ELECTRONIC STRUCTURE AND CHARGE TRANSPORT MECHANISM IN SILICON NITRIDE AND OXYNITRIDE

摘要

The short-range order in silicon nitride with varying oxygen concentrations (SiO_xN_y and SiN_x) is studied by high resolution X-ray photoelectron spectroscopy (XPS). The SiO_xN_y short range order is quantitatively described by the random bonding model. In contrast, the SiN_x structure cannot be explained on the basis of the random bonding and random mixture models. Usually the charge transport in Si_3N_4 is explained by the Frenkel model of trap ionization, but we have found that this model gives an unphysically low attempt-to-escape frequency and an enormously large electron effective mass. Therefore the multi-phonon assisted ionization model was proposed, which is in agreement with the experimental data on the electron transport in the nitride.