High-detectivity, normal-incidence, mid-infrared (λ∼4 μm)InAs/GaAs quantum-dot detector operating at 150 K

Normal-incidence InAs/GaAs quantum-dot detectors have been grown, fabricated, and characterized for mid-infrared detection in the temperature range from 78 to 150 K. Due to the presence of an ${\mathrm{Al}}_{\mathrm{0.3}}{\mathrm{Ga}}_{\mathrm{0.7}}\mathrm{As}$ current blocking layer in the heterostructure, the dark current is very low, and at $\text{T=100\hspace{0.05em}}\mathrm{K},$ $I_{\mathrm{dark}}\text{=1.7\hspace{0.05em}}\mathrm{pA}$ for $V_{\mathrm{bias}}\text{=0.1\hspace{0.05em}}\mathrm{V}.$ The peak of the spectral response curve is at $\text{λ∼4\hspace{0.05em}μ}\mathrm{m},$ with $\text{Δλ/λ=0.3}$ and $V_{\mathrm{bias}}\text{=0.1\hspace{0.05em}}\mathrm{V}.$ At $\text{T=100\hspace{0.05em}}\mathrm{K},$ for $V_{\mathrm{bias}}\text{=0.3\hspace{0.05em}}\mathrm{V},$ the peak detectivity, $D^{*},$ is ${\text{3×10}}^9 {\mathrm{cm Hz}}^{\text{1/2}}/\mathrm{W},$ and the peak responsivity, $R_p,$ is 2 mA/W with a photoconductive gain of $\text{g=18.}$