Hot-electron micro & nanobolometers based on low-mobility 2DEG for high resolution THz spectroscopy

The results on design, fabrication, and characterization of a hot-electron bolometer (HEB) based on the low-mobility two-dimensional electron gas (2DEG) in a AlGaN/GaN heterostructures show that our HEBs have high coupling to incident THz radiation due to the Drude absorption. Significant heating by THz radiation is realized due to the small value of the electron heat capacity. A low contact resistance achieved in our devices ensures that the THz radiation couples primarily to the 2DEG. Due to the small electron momentum relaxation time, the real part of the 2DEG sensor impedance is 50-100 Ω, which provides a good impedance match between the sensor and antenna. Currently the room temperature responsivity of our devices reaches 0.04 A/W at 2.55 THz along with a noise equivalent power 5 nW/Hz^1/2 at room temperature.