Detection of Terahertz Radiation with Two-Dimensional Plasmons in Multi-Gate High Electron Mobility Transistors

We have successfully fabricated and characterized monolithic plasmonic terahertz detectors that exhibit a narrowband, tunable plasmonic response. These detectors are based upon multi-gate GaAs/AlGaAs high electron mobility transistors where gate geometry and bias permit both excitation and detection of resonant 2D terahertz plasmons. Substantially improved responsivity is achieved through the use of a lateral potential barrier that is controlled by an independently biased, narrow gate adjacent to the drain. Bias-dependent terahertz responsivity and time constant measurements combined with DC electrical characterization indicate that a hot electron bolometric effect is the dominant response mechanism.;Work also focused upon antenna coupled multi-gate high electron mobility transistors. The integration of a broadband log-periodic antenna permits improved coupling of terahertz radiation while maintaining the tunability and bolometric response of the previous generation of this class of detector. Incident terahertz radiation may excite 2D plasmons with wave-vectors defined by the geometry and bias of the gate, source and drain terminals. With a short channel geometry, we have observed multiple harmonics of terahertz plasmons associated with a resonant cavity. At 20 K with detector bias optimized we report a responsivity on resonance of up to 7 kV/W and an NEP of 5 x 10-10 W/Hz 1/2.