AlGaAs emitter/GaAs barrier terahertz detector with a 2.3 THz threshold

A heterojunction interfacial work function internal photoemission (HEIWIP) detector with a threshold frequency (f(0)) of 2.3 THz (lambda(0) = 128 Am) is demonstrated. The threshold limit of similar to3.3 THz (92 mum) due to the Al fraction being limited to similar to0.005, in order to avoid control and transition from alloy to isoelectronic doping behavior, was surpassed using AlGaAs emitters and GaAs barriers. The peak values of responsivity, quantum efficiency, and the specific detectivity at 9.6 THz and 4.8 K for a bias field of 2.0 kV/cm are 7.3 A/W, 29%, 5.3 x 10(11) Jones, respectively. The background-limited infrared photodetector temperature of 20 K with a 60 field of view was observed for a bias field of 0.15 kV/cm. The f(0) could be further reduced toward similar to1 THz regime (similar to300 mum) by adjusting the Al fraction to offset the effect of residual doping, and/or lowering the residual doping in the barrier, effectively lowering the band bending. (C) 2005 American Institute of Physics.