Single and Multi Emitter Terahertz Detectors Using n-Type GaAs/AlGaAs Heterostructures

Terahertz detection is demonstrated using GaAs/Al_xGa_1-xAs n-type heterojunction interfacial work function internal photoemission (HEIWIP) detectors. A smaller work function (Delta) needed for terahertz detection can be achieved by using n-doped GaAs emitter and undoped Al_xGa_1-xAs barrier. A single emitter and a multi emitter n-type GaAs/Al_xGa_1-xAs HEIWIP detectors were designed, fabricated and characterized. In both designs, 1times10¹⁸ cm^-3 n-type doped GaAs was used as the emitter while Al_xGa_1-xAs with x = 0.04 for the single emitter detector and x=0.13 for the multi emitter detector was used as the barrier. The threshold frequency of 3.2 THz (93 mum ) with peak responsivity of 6.5 A/W at 7.1 THz at 6 K was successfully demonstrated for the single emitter detector while 5 THz (60 mum) threshold frequency and 0.32 A/W peak responsivity was observed for the multi emitter detector at 5 K. In addition, the peak quantum efficiency of ~19% and peak detectivity of ~5.5times10⁸ Jones under a bias field of 0.7 kV/cm at 6 K were obtained for the single emitter detector.