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 Al0.3Ga0.7As 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∗ = 2.3×1010 cm Hz1/2/W in the dark is measured. The TBLIP of the device is 60 K and the D∗ at this temperature is 2×109 cm Hz1/2/W.