Plasmonic terahertz detectors based on a high-electron mobility GaAs/AlGaAs heterostructure

摘要

In order to characterize magnetic-field (B) tunable THz plasmonic detectors,spectroscopy experiments were carried out at liquid helium temperatures andhigh magnetic fields on devices fabricated on a high electron mobilityGaAs/AlGaAs heterostructure. The samples were either gated (the gate of ameander shape) or ungated. Spectra of a photovoltage generated by THz radiationwere obtained as a function of B at a fixed THz excitation from a THz laser oras a function of THz photon frequency at a fixed B with a Fourier spectrometer.In the first type of measurements, the wave vector of magnetoplasmons excitedwas defined by geometrical features of samples. It was also found that themagnetoplasmon spectrum depended on the gate geometry which gives an additionalparameter to control plasma excitations in THz detectors. Fourier spectrashowed a strong dependence of the cyclotron resonance amplitude on theconduction-band electron filling factor which was explained within a model ofthe electron gas heating with the THz radiation. The study allows to defineboth the advantages and limitations of plasmonic devices based on high-mobilityGaAs/AlGaAs heterostructures for THz detection at low temperatures and highmagnetic fields.