A high performance quantum-well infrared photodetector detecting below 4.1 mu m

We demonstrate a high performance quantum-well infrared photodetector on GaAs(0 0 1) substrate, with a spectral response peaked below the carbon dioxide absorption band. The active layer is based on an AlGaAs/AlAs/InGaAs/AlAs/AlGaAs quantum well and designed to achieve a bound to quasi-bound transition. The external quantum efficiency measured at 130 K and -1 V is as high as 21%, leading to peak absorption higher than 28% when an anti-reflection coating is used. The background limited peak detectivity reaches 7 x 10(11) Jones (cm Hz(1/2) W(-1)) at 77 K and f/1.6. The detector operates in the background limited regime up to 100 K. Our measured characteristics are key inputs to estimate the performance of a thermal imager and are directly useable by system designers.