CMOS Integrated Antenna-Coupled Field-Effect Transistors for the Detection of Radiation From 0.2 to 4.3 THz

This paper reports on field-effect-transistor-based terahertz detectors for the operation at discrete frequencies spanning from 0.2 to 4.3 THz. They are implemented using a 150-nm CMOS process technology, employ self-mixing in the n-channels of the transistors and operate well above the transistors' cutoff frequency. The theoretical description of device operation by Dyakonov and Shur is extended in order to describe the device impedance, responsivity, and noise-equivalent power for a novel detection concept, which couples the signal to the drain. This approach enables quasi-static (QS) detection and calibration of the detectors. The different transport regimes (i.e., QS, distributed resistive, and plasmonic mixing) and their transitions are theoretically discussed and experimentally accessed. Responsivity values of 350 V/W at 595 GHz, 30 V/W at 2.9 THz, and 5 V/W at 4.1 THz are reported. At 0.595 THz, we determine the optical noise equivalent power (NEP) to be 42 pW/root Hz; at 2.9 THz, the value is 487 pW/root Hz. All values are reported for optimum gate bias with respect to NEP at 295 K. For 0.595 THz, theory predicts a NEP value at threshold as low as 2 pW/root Hz for ideal coupling of the radiation.