High-detectivity, normal-incidence, mid-infrared (λ∼4 μm)InAs/GaAs quantum-dot detector operating at 150 K

Normal-incidence InAs/GaAs quantum-dot detectors have been grown, fabricated, and characterized for mid-infrared detection in the temperature range from 78 to 150 K. Due to the presence of an Al0.3Ga0.7As current blocking layer in the heterostructure, the dark current is very low, and at T=100 K, I-dark=1.7 pA for V-bias=0.1 V. The peak of the spectral response curve is at lambda similar to4 mum, with Delta lambda/lambda =0.3 and V-bias=0.1 V. At T=100 K, for V-bias=0.3 V, the peak detectivity, D*, is 3x10(9) cm Hz(1/2)/W, and the peak responsivity, R-p, is 2 mA/W with a photoconductive gain of g=18. (C) 2001 American Institute of Physics.