InAs quantum dot infrared photodetectors with In0.15Ga0.85As strain-relief cap layers

We report InAs quantum dot infrared photodetectors that utilize In0.15Ga0.85As strain-relief cap layers. These devices exhibited normal-incidence photoresponse peaks at 8.3 or 8.8 mum for negative or positive bias, respectively. At 77 K and -0.2 V bias the responsivity was 22 mA/W and the peak detectivity D-* was 3.2x10(9) cm Hz(1/2)/W. (C) 2002 American Institute of Physics.