Characteristics of self-assembled InGaAs InGaP quantum dot mid-infrared photoconductive detectors grown by low pressure MOCVD

We report the first self-assembled InGaAs/InGaP quantum dot intersubband infrared photoconductive detectors (QDIPs) grown on semi-insulating GaAs substrate by low pressure metal organic chemical vapor deposition (MOCVD). The InGaAs quantum dots were constructed on an InGaP matrix as self assembling in Stranski-Krastanow growth mode in optimum growth conditions. The detector structure was prepared for single layer and multi-stacked quantum dots for active region. Normal incident photoconductive response was observed at a peak wavelength of 5.5 mu m with a high responsivity of 130mA/W, and a detectivity of 4.74 x 10(7) cm Hz(1/2)/W at 77K for multi-stack QDIP. Low temperature photoresponse of the single quantum dot photodetector was characterized. Peak response was obtained between 16K and 60K. The detailed dark current noise measurements were carried on single and multistack quantum dot infrared detectors. High photoconductive gain as 7.6 x 10(3) biased at 0.5V results in increasing the intersubband carrier relaxation time as two order of magnitude compared quantum well infrared photodetectors.