Ultrahigh-performance superlattice mid-infrared nBn photodetectors at high operating temperatures

Abstract

While advancing a physics-based comprehensive photodetector-simulation model, we propose a novel device design of the mid-wavelength infrared nBn photodetectors by exploiting the inherit flexibility of the $InAs_{1-x}Sb_{x}$ ternary alloy material system. To further explicate the physics of such photodetectors, we calculate several crucial transport and optoelectronic parameters, including the dark current density, absorption coefficient, responsivity, and the quantum efficiency of nBn photodetectors. A remarkable maximum efficiency of 57.39\% is achieved at room temperature at a bias of -0.25 V, coupled with a radiation power density of 50 mW/$cm^{2}$. The proposed structure features a maximum quantum efficiency of 44.18\% and 37.87\% at 60\% and 70\% of the $\lambda_c$, respectively. Furthermore, a maximum responsivity of 0.9257 A/W is shown within the mid-wavelength infrared spectrum. Through our comprehensive analysis, we also demonstrate that our proposed device design effectively reduces the dark current density by confining the electric field inside the barrier while preserving a superior level of quantum efficiency, and the current in such detectors is diffusion-limited. Insights uncovered here could be of broad interest to critically evaluate the potential of the nBn structures for mid-wavelength infrared photodetectors.