Probing the N-induced states in dilute GaAsN alloys by magneto-tunnelling

We use a combination of magneto-tunnelling and photoluminescence spectroscopy techniques to explore the admixing of the extended GaAs conduction band states with the localised N-impurity states in dilute GaAs1−yNy quantum wells (QWs) incorporated in resonant tunnelling diodes. When y is increased from 0% to 0.08%, the current resonance due to electrons tunnelling through the lowest quasi-bound state of the QW splits into two main features due to electron tunnelling into the N-induced E− and E+ hybridised subbands of the GaAs1−yNy layer. These subbands have a very well-defined character even for a small N-content (∼0.08%) and have non-parabolic energy–momentum dispersions. A further increase of y smears out the resonances and quenches the current due to electron trapping on strongly localised N-levels.