Strained InGaAs/AlGaAs quantum well infrared detectors at 4.5 μm

Abstract
We demonstrate midinfrared photodetection at λ=4.5 μm in a multi-quantum well detector using a strained InGaAs/AlGaAs alloy grown on a GaAs substrate. The detector shows very low dark current of a few pA, a peak unpolarized light responsivity R=12 mA/W for an external 45° angle of incidence, and a background-limited detectivity D*BL=4×1010 cm Hz1/2/W at temperatures up to 95 K in the same conditions. This opens the way to high performance 3–5 and 8–12 μm GaAs-based multispectral detectors