Anomalous ambipolar transport in depleted GaAs nanowires

We have used a polarized microluminescence technique to investigate photocarrier charge and spin transport in n-type depleted GaAs nanowires ($ \approx 10^{17}$ cm$^{-3}$ doping level). At 6K, long-distance tail appears the luminescence spatial profile, indicative of transport, only limited by length NW. This is independent on excitation power temperature. Using self-consistent calculation based drift-diffusion Poisson equations as well statistics (Van Roosbroeck model), it found that this due drift an internal electric field nearly two orders magnitude larger than fields predicted usual ambipolar model. large because effects. Firstly, for fluctuations conduction band minimum valence maximum, electron mobility activated field. implies, counter intuitive way, favor long distance transport. Secondly, range carrier further increased finite NW length, effect which plays key role one-dimensional systems.