  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.
