Low dark current InAs/GaAs quantum dot infrared photodetector (QDIP) is dem
onstrated. The dark current reduced for over three orders of magnitude by i
ntroducing a thin AlGaAs current blocking layer. This thin AlGaAs can reduc
e the dark current much more than the response signal. The responsivity at
0.5 V is 0.08 A/W with peak at 6.5 mum and the corresponding detectivity ab
out 2.5 x 10(9) cm Hz(1/2/W1/2). It is the highest detectivity reported for
QDIP at 77 K. (C) 2001 Published by Elsevier Science B.V.