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We have investigated the effects of N on the electronic properties of Si-doped GaAs1-xNx alloy films and AlGaAs/GaAsN modulation-doped heterostructures. For bulk-like alloy films, the electron mobility is independent of free carrier concentration and arsenic species, and decreases with increasing N composition. Thus, N-related defects are the main source of scattering in the dilute nitride alloys. For AlGaAs/GaAsN heterostructures, gated and illuminated magnetoresistance measurements reveal a two-dimensional electron gas mobility which increases with carrier concentration to a constant value. Thus, in contrast to the long-range ionized scattering sources which are dominant in N-free heterostructures, N-induced neutral scattering sources are the dominant source of scattering in AlGaAs/GaAsN heterostructures. Finally, a decrease in free carrier concentration with increasing N composition is apparent for bulk-like films, while the free carrier concentration is independent of N composition in modulation-doped heterostructures. Since N and Si atoms are spatially separated in the modulation-doped heterostructures, N–Si defect complexes in the bulk GaAsN layers are likely acting as trapping centers. [ABSTRACT FROM AUTHOR]

We have investigated the influence of Si–N complexes on the electronic properties of GaAsN alloys. The presence of Si–N complexes is suggested by a decrease in carrier concentration, n, with increasing N-composition, observed in GaAsN:Si films but not in modulation-doped heterostructures. In addition, for GaAsN:Te (GaAsN:Si), n increases substantially (minimally) with annealing-T, suggesting a competition between annealing-induced Si–N complex formation and a reduced concentration of N-related traps. Since Si–N complex formation is enhanced for GaAsN:Si growth with the (2×4) reconstruction, which has limited group V sites for As–N exchange, the (Si–N)As interstitial pair is identified as the dominant Si–N complex. [ABSTRACT FROM AUTHOR]