We present a systematic study of low-frequency noise in Au nanoparticle chemosensors. All the sensors we have studied exhibit 1∕f-type noise at low frequencies. The magnitude of the 1∕f noise was smaller in devices with a larger device area, indicating that the 1∕f noise is caused by intrinsic processes. The noise amplitude was found to be strongly temperature dependent between 40–300K, with a local peak at around 100K, and weakly dependent below 40K. The noise data could not be fit by a single activated process indicating that multiple noise processes must be present in our sensors.

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.

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