Multispectral operation of self-assembled $InGaAs$ quantum-dot infrared photodetectors

We report two-color $InGaAs$ quantum-dot infrared photodetectors. The $InGaAs$ self-assembled quantum dots were grown on $InGaP$ matrix via metalorganic chemical vapor deposition and fabricated as intersubband photoconductive structure. Bias controlled two-color photoconductive responses were obtained at two different infrared window, mid-infrared (IR) of $λ=5.5μm$ and far-IR of $λ=9.2μm$ at $77K$⁠. Our devices were operated with low dark currents and high optical gains, and resulted in peak detectivity, $D*$⁠, of $4.7×109cmHz1∕2∕W$ at $λ=5.5μm$ with bias of $−2.0V$⁠, and $7.2×108cmHz1∕2∕W$ at $λ=9.2μm$ with bias of $−0.8V$⁠.