Design and Performance Characteristics of Quantum Well Infra-Red Photodetectors

We present studies on the effect of design parameters on the performance of quantum well-infrared photodetectors (QWIP) based on InxGa1–xAs / InP material system, with the objective of achieving an optimum design to detect long-wavelength infrared radiation in the range 5 µm to 7 µm. Through an optimum design and simulations for QWIP, we are able to achieve a peak responsivity of 1.75 Amp/Watt at 6.5 µm wavelength, a dark current of 0.7 pA (at 2 V) at 77 K, and a detectivity of 7.12 × 1013 (cm- Hz−1/2/Watt) with detector area 3.1 × 10–4 cm2, indicating high sensitivity to IR radiation. We have also studied cascaded QWIP for which an average responsivity greater than 3.61 Amp/Watt within the detection bandwidth, and a dark current of 13.65 nA at 77 K is obtained.