First-principles investigation ofa−SiNx:H

We carried out a theoretical investigation on the electronic properties of hydrogenated amorphous silicon nitride $(a-{\mathrm{SiN}}_x:\mathrm{H},$ $0.5<x<\mathrm{}1.8).\mathrm{}$ The calculations were performed by combining interatomic potentials and first-principles methods. We present the trends in the electronic band structure of ${\mathrm{SiN}}_x;$ the behavior of the energy gap as a function of the nitrogen content was in good agreement with experimental results. Hydrogenation was found to reduce considerably the number of energy levels in the material’s gap. The energy levels, which appeared in the band gap, were compared to electrically active centers, detected by electron-paramagnetic-resonance experiments.