Wavelength-tunable InGaAs-capped quantum-dot infrared photodetectors for multi-color detection

A two-terminal quantum-dot infrared photodetector (QDIP) with stacked 5-period InAs/GaAs and InGaAs-capped InAs/GaAs QD structures is investigated in this paper. The device has exhibited distinct responses at mid-wavelength and long-wavelength infrared regions under positive and negative biases, respectively. Also observed for the device are the equal normal absorption ratios under different voltage biases for the device under either MWIR or LWIR ranges. The device has revealed its potential in the application of voltage-tunable and multi-color detections.