Long-Wave Infrared Sub-Monolayer Quantum Dot Quantum Cascade Photodetector

In this article, a long-wave infrared InAs/GaAs sub-monolayer quantum dot quantum cascade photodetector (SML QD-QCD) grown on GaAs substrate is demonstrated. Temperature- and excitation-dependent photoluminescence measurements are used to study the optical properties of the quantum dot active region, which reveal energetically hybrid ground states between the InAs quantum dot and InGaAs quantum well due to the possible inter-mixing of In and Ga atoms during growth process. The device covers a spectral region from 6.5 to 9 μm. At 77 K, a peak responsivity of 7.5 mA/W is found at 8.3 μm (0 V) and a zero-bias differential-resistance-area (R 0 A) product of 9008 Ω·cm 2 is obtained. The white noise-limited detectivity is 6.5 × 10 9 cm·Hz 1/2 /W. These results encourage the SML QD-QCD as a strong competitor for long-wave infrared imaging applications that require normal incidence and low power dissipation.