Design, fabrication, and characterization of quantum well infrared photoconductor in long-wavelength infrared

Optimum quantum well infrared photodetectors (QWIP) structure parameters such as well width and barrier height for a given peak detection wavelength of 8 μm were designed, based on which GaAs/AlGaAs material with designed structure was grown and single element QWIP devices were fabricated. In order to accurately calculate the optimum QWIP structure parameters including well width, barrier height and doping density etc., we took into account higher order effects such as band nonparabolicity in our calculations. One band effective mass approximation was employed in modeling and shooting method was used in calculation. We fabricated three kinds of QWIP samples that have 20, 40 and 60 periods of quantum wells respectively. I-V characteristic curves and photoresponse at different temperature were measured to characterize the detectors. A peak detectivity of 8×1010 cmHz1/2/W was demonstrated by one of our QWIP devices. Besides, the varying performance of the three samples due to the different repeats of wells is discussed in this paper.