Asymmetric heterostructure for photovoltaic InAs quantum dot infrared photodetector

摘要

A photovoltaic InAs quantum dot-under-a-well photodetector is reported with a peak responsivity at 7 μm 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 × 10~(10)cm Hz~(1/2)/W in the dark is measured. The T_(NLIP) of the device is 60 K and the D~* at this temperature is 2 × 10~9 cm Hz~(1/2)/W.