A two-stack, three-color quantum well infrared photodetector for mid- and long-wavelength infrared detection

In this paper we report a high performance 2-stack, 3-color quantum well infrared photodetector (QWIP) composed of an InGaAs/AlGaAs QWIP and an InGaAs/AlGaAs/InGaAs triple-coupled (TC-) QWIP grown on the GaAs substrate for the mid- and long-wavelength (MW/LW) infrared (IR) detection. The basic device structure consists of a MWIR QWIP stack with 3 periods of a 43Angstrom In0.3Ga0.7As quantum well and an undoped 300Angstrom Al0.3Ga0.7As barrier and a LWIR TC-QWIP stack with 5 periods of a 65Angstrom In0.18Ga0.82As quantum well (QW) and two undoped 60Angstrom In0.05Ga0.95As QWs separated by 20Angstrom Al0.08Ga0.92As barriers. The TC-QWIP stack has two response peaks, which are voltage-tunable from 9.2mum to 10mum and 12mum to 12.2mum by the applied bias, respectively. For the LWIR TC-QWIP, a maximum responsivity of 1.96A/W at 12mum was obtained at T = 40K, and a maximum detectivity of D-* = 1.59 x 10(10)cm(.)Hz(1/2)/W was obtained at V-b = -1.7V, lambda(p) = 12mum, and T = 20K. As for the MWIR QWIP stack excellent responsivity at the peak wavelength of lambda(p) = 5.1mum was obtained up to 120K.