  We study using first-principles calculations the energetics, structural and
electronic properties of nitrogen incorporation in SiO2. We consider NO, NH, N2
and atomic N as the nitriding species interacting with a Si-Si bond of an
otherwise perfect SiO2 network in order to simulate the nitrogen incorporation
near Si/SiO2 interface regions. We find that all the species react with the
Si-Si bond forming bridge structures with the Si atoms without dissociating,
where NH and atomic N form the most stable structures. Concerning the
electronic properties, our results show that the incorporated NH is the only
structure which does not introduce trapping center at the interface. The
structures involving NO and atomic N are acceptors, whereas that involving N2
may be either a donor or an acceptor. The hydrogen passivation of the
electrically active centers is also discussed.
