Two-stack indirect-barrier/triple-coupled quantum well infrared detector for mid-wavelength and long-wavelength infrared dual band detection

We report a two-stack indirect-barrier (IB) GaAs/AlGaAs quantum well infrared photodetector (QWIP) for mid-wavelength infrared (MWIR) and a voltage-tunable InGaAs/GaAs/AlGaAs triple-coupled (TC) QWIP for long-wavelength infrared (LWIR) detection. The peak responsivity of the stacked QWIP at zero bias (PV mode) was found to be 30 mA/W at lambda(p)=4.3 mu m and T=40 K. The maximum peak responsivity for the stacked QWIP was found to be 0.21 A/W at lambda(p)=4.3 mu m, V-b=4 V, and T=40 K. For the LWIR TC-QWIP, the peak detection wavelength due to (E-1-->E-3) transition shifts from 10 to 9.4 mu m as bias voltage increases from 7 to 12 V. The maximum responsivity was found to be 0.085 A/W at lambda(p)=9.4 mu m, V-b = 12 V, and T= 40 K. The results show that simultaneously detection of both the MWIR and LWIR bands can be achieved at V-b greater than or equal to 7 V or V-b less than or equal to-5 V. It is shown that this two-stack QWIP can be used as a voltage-tunable two-color or multicolor QWIP for the MWIR and LWIR dual band detection. (C) 1997 American Institute of Physics. [S0003-6951(97)03950-8].