(Invited) Plasmonic Terahertz Detectors

We review the achieved and potential performance of plasmonic terahertz detectors implemented in III-N, III-V, Si, and graphene materials systems and operating in the overdamped and resonant regimes. Such detectors have been using single transistors and transistor arrays. They operated in a wide temperature range – from cryogenic to elevated temperatures – and in the frequency range from 0.2 THz to 5 THz with Noise Equivalent Powers as low as 1 pW/Hz^1/2. The modulation frequency over 10 GHz has been achieved. The predicted modulation frequencies reach into the THz range.  Each materials system (III-N, III-V, and Si) has its optimum frequency range of operation. High mobility InGaAs plasmonic HEMT detectors are expected to operate efficiently up to 10 THz and higher. For the III-N plasmonic transistors, the operation range could reach or exceed 1 or 2 THz. Si CMOS could work as efficient plasmonic THz detectors up to 1 THz or higher. The optimum channel length for each frequency range depends on the materials system. The device responsivity peaks near or slightly below the threshold voltage and is greatly enhanced by driving drain or gate currents due to the increased non-linearity (in the case of the drain current) and due to the induced phase shift (in the case of the gate current). The detection of single THz pules with plasmonic detectors has also been achieved. These THz detectors are expected to find numerous applications in sensing, imaging, wireless communications, and security systems.