Plasmonic Terahertz Detector with an Integrated Hot Electron Bolometer

We have characterized a tunable, narrowband, grating-gated high electron mobility transistors (HEMT) that detects terahertz radiation. Detectors of this class aid in filling the technology gap of the terahertz band of the electromagnetic spectrum, which is limited in terms of both detectors and sources. A grating gate on the detector resonantly couples terahertz radiation to 2D plasmons. An additional independently-biased gate produces a bolometric element that senses the absorption of terahertz radiation. The terahertz responsivity follows dV/dT as a measure of temperature induced change in the voltage. This confirms that the response mechanism is bolometric. Detector response time measured under terahertz illumination is proportional to dV/dI, the differential resistance, which indicates the response time is an “RC” circuit time constant. Taken together, this data shows that this integrated plasmonic detector behaves as a hot electron bolometer. With further optimization to improve sensitivity, these tunable, fast, narrowband detectors will lead to chip-based terahertz spectroscopy for a variety of purposes including research on protein dynamics, biological and chemical detection for homeland security, and medical diagnostics.