High-performance quantum ring detector for the 1–3 terahertz range

Abstract

Molecular beam epitaxy of InAs/GaAs quantum dots and their subsequent transformation to quantum rings by postepitaxy thermal annealing have been investigated. Photoconductive detectors with multiple quantum ring layers in the active region exhibit dark current density ∼10−8 A/cm2 at a bias of 2 V at 4.2 K. The rings have a single bound state, and emission of photoexcited carriers gives rise to a spectral response peaking at 1.82 THz (165 μm) at 5.2 K. Peak responsivity of 25 A/W, specific detectivity, D∗, of 1×1016 Jones and a total quantum efficiency of 19% are measured with 1 V bias at 5.2 K. At 10 K and 1 V, D∗∼3×1015 Jones is measured.