n-type GaAs/AlGaAs heterostructure detector with a 3.2 THz threshold frequency

Terahertz detection using the free-carrier absorption requires a small internal work function of the order of a few millielectron volts. A threshold frequency of 3.2 THz (93 mu m or similar to 13 meV work function) is demonstrated by using a 1 X 10(18) cm(-3) Si-doped GaAs emitter and an undoped Al0.04Ga0.96As barrier structure. The peak responsivity of 6.5 A/W, detectivity of 5.5 X 10(8) Jones, and quantum efficiency of 19% were obtained at 7.1 THz under a bias field of 0.7 kV/cm at 6 K, while the detector spectral response range spans from 3.2 to 30 THz. (C) 2007 Optical Society of America