Asymmetric heterostructure for photovoltaic InAs quantum dot infrared photodetector

A photovoltaic InAs quantum dot-under-a-well photodetector is reported with a peak responsivity at 7 mu m wavelength. In this structure, we implement an improved injection scheme, which allows a controlled feeding of the quantum dots through a modulation-doped InGaAs quantum well injector. A thin Al(0.3)Ga(0.7)As barrier significantly reduces the dark current and, at the same time, is responsible for the photovoltaic behavior. At 4 K and no applied bias, a responsivity of 2.5 mA/W and a detectivity of D* = 2.3 x 10(10) cm Hz(1/2)/W in the dark is measured. The T(BLIP) of the device is 60 K and the D* at this temperature is 2 x 10(9) cm Hz(1/2)/W. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3462960]