Nitrogen-induced levels inGaAs1−xNxstudied with resonant Raman scattering

Resonant Raman scattering is used to study the nature of the recently discovered nitrogen-induced level $E_{+}$ located in the conduction band of ${\mathrm{GaAs}}_{1-x}{\mathrm{N}}_x$ $(0.001\mathrm{}<~x<~0.022).$ Our data demonstrate that the $E_{+}$ state is derived from the nitrogen-induced $\Gamma$-$L$ mixing of the bulk GaAs states and that it is not an isolated nitrogen impurity level. A broadening of the GaAs-like longitudinal-optical phonon line and an enhancement of the transverse-optical phonon line is observed near resonance, which is interpreted as being due to resonance with strongly localized states.