A quantum ring detector for the 1–3 terahertz range with very high responsivity and specific detectivity

The detection of long wavelength and terahertz (THz) radiation is important for a number of applications including molecular spectroscopy, medical diagnostics, security and surveillance, quality control, and astronomy. Semiconductor based quantum dot (QD) and quantum ring (QR) detectors [1, 2] have been used for the detection of long wavelength radiation. While high temperature operation of the devices is desired for some applications, THz detectors operating at low temperatures are also in demand, particularly for astronomy and space applications. Another challenge for semiconductor-based detectors is operation in the 1–3 THz range. We report here a InAs/GaAs quantum ring intersublevel detector (QRID) with spectral response peaking at 1.82 THz (165 µm) and having a peak responsivity Rp of 25 A/W and specific detectivity D* of 1×1016 Jones for 1 V bias at 5.2 K. At 10 K, the spectral response peaks at 2.4 THz (125 µm) with Rp = 3 A/W and D* = 3×1015 Jones. These characteristics compare very favorably with those of bolometers that are currently used.