Short-range order and luminescence in amorphous silicon oxynitride

Using Si 2p core-level X-ray photoelectron spectroscopy, we found that the short-range order in amorphous silicon oxynitride (a-SiO_xN_y) can be quantitatively described by a random bonding model. Results also show that the second and even further neighbours of the Si in the network affect the chemical shifts of the X-ray photoelectron spectra. Cathodoluminescence and photoluminescence of a-SiO_xN_y with different compositions are also measured. A red band with energies of 1.8-1.9 eV, a blue band with an energy of 2.7 eV and ultraviolet bands with energies of 13.1, 3.4-3.6, 4.4-4.7 and 5.4 eV were observed. The 1.8-1.9eV band is attributed to the O and N atoms with an unpaired electron and the 2.7 eV band is attributed to the twofold-coordinated Si atom with two electrons (sililene centre). The ultraviolet bands are assumed to be related in the Si Si bonds.