Raster-scan imaging with normal-incidence, midinfrared InAs/GaAs quantum dot infrared photodetectors

We demonstrate normal incidence infrared imaging with quantum dot infrared photodetectors using a raster-scan technique. The device heterostructure, containing multiple layers of InAs/GaAs self-organized quantum dots, were grown by molecular-beam epitaxy. Individual devices have been operated at temperatures as high as 150 K and, at 100 K, are characterized by λpeak=3.72 μm, Jdark=6×10−10 A/cm2 for a bias of 0.1 V, and D*=2.94×109 cm Hz1/2/W at a bias of 0.2 V. Raster-scan images of heated objects and infrared light sources were obtained with a small (13×13) interconnected array of detectors (to increase the photocurrent) at 80 K.