We report cyclotron resonance ͑CR͒, transverse magnetoresistance ͑MR͒, and Hall effect studies of a series of n-type InAs 1−x N x epilayers grown on GaAs with x up to 1%. The well-resolved CR absorption lines, the classical linear MR, Shubnikov-de Haas magneto-oscillations, and negative MR revealed in our experiments provide a means of probing the effect of the N atoms on the electronic properties of this alloy system and reveal qualitative differences compared to the case of the wider gap III-N-V compounds, such as GaAs 1−x N x . In GaAs 1−x N x electron localization by N levels that are resonant with the extended band states of the host crystal act to degrade the electrical conductivity at small x ͑ϳ0.1%͒. These phenomena are significantly weaker in InAs 1−x N x due to the smaller energy gap and higher energy of the N levels relative to the conduction band minimum. In InAs 1−x N x the electrical conductivity retains the characteristic features of transport through extended states, with electron coherence lengths ͑l ϳ 100 nm at 2 K͒ and electron mobilities ͑ =6 ϫ 10 3 cm 2 V −1 s −1 at 300 K͒ that remain relatively large even at x =1%.

Band structure engineering of superlattice-based short-, mid-, and long-wavelength infrared avalanche photodiodes for improved impact ionization ratesWe report an experimental study of hot electron dynamics in the narrow band gap dilute nitride alloy, InAs 1−x N x , with x up to 0.6%. The sharp increase in the conductivity of n-type InAs 1−x N x at applied electric fields above 1 kV/cm demonstrates that impact ionization dominates the hot electron dynamics. This observation, combined with the reduction in the band gap energy by the N-atoms, suggest prospects for the use of this narrow gap alloy in infrared avalanche photodiodes.

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A study of magnetotunnelling in weakly coupled multi-quantum wells reveals a new phenomenon which constitutes a kind of memory effect in the sense that the electrical resistance of the sample after application of the magnetic field is different from before and contains the information that a magnetic field was applied previously. The change in the electric field domain configuration triggered by the magnetic field was compared for two samples, one strictly periodic and another with a thicker quantum well inserted into the periodic structure. For applied biases at which two electric field domains are present in the sample, as the magnetic field is increased a succession of discontinuous reductions in the electrical resistance is observed due to the magnetic field-induced rearrangement of the electric field domains, i.e. the domain boundary jumps from well to well as the magnetic field is changed. The memory effect is revealed for the aperiodic structure as the electric field domain configuration triggered by the magnetic field remains stable after the field is reduced back to zero. This effect is related to the multi-stability in the current–voltage characteristics observed in some weakly coupled multi-quantum well structures.

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