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The use of a high-electron mobility semiconductor nanowire as transistor channel has recently allowed the extension of the spectral coverage of THz field-effect transistor detectors up to 1.5 THz. In this report, we demonstrate efficient operation of a field-effect transistor detector based on a semiconductor nanowire at a much higher frequency, 2.8 THz, with a responsivity ?5 V/W in a bandwidth ?100 kHz, thus proving the full potential of such approach for the detection of THz quantum cascade lasers. Finally, such a THz sensing system is exploited to perform raster scan transmission imaging, with high spatial resolution, signal-to-noise ratio, and acquisition rate. © 2014 AIP Publishing LLC.

InSb-InAs nanowire heterostructure diodes investigated by electron beam induced current (EBIC) demonstrate an unusual spatial profile where the sign of the EBIC signal changes in the vicinity of the heterointerface. A qualitative explanation confirmed by theoretical calculations is based on the specific band diagram of the structure representing a type-III heterojunction with an accumulation layer in InAs. The sign of the EBIC signal depends on the specific parameters of this layer. In the course of measurements, the diffusion length of holes in InAs and its temperature dependence are also determined.