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 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 43 Angstroms In0.3Ga0.7As quantum well and an undoped 300 Angstroms Al0.3Ga0.7As barrier and a LWIR TC-QWIP stack with 5 periods of 65 Angstroms In0.18Ga0.82As quantum well (QW) and two undoped 60 Angstroms In0.05Ga0.95As Qws separated by 20 Angstroms Al0.08Ga0.92As barriers. The TC-QWIP stack has two response peaks, which are voltage-tunable from 9.2micrometers to 10 micrometers and 12micrometers to 12.2micrometers by the applied bias, respectively. For the LWIR TC-QWIP, a maximum responsivity of 1.96A/W at 12micrometers was obtained at T=40K, and a maximum detectivity of (Formula available in paper) was obtained at Vb=-1.7V, λp=12micrometers , and T=20K. As for the MWIR QWIP stack excellent responsivity at the peak wavelength of λp=5.1micrometers was obtained up to 120 K.