Modeling of dark current suppression in unipolar barrier infrared detectors

In this paper, the physical mechanism of unipolar barrier structures is elaborated for dark current suppression. To better understand the performance characteristics of the devices and optimize the structures, we have performed numerical drift-diffusion simulations of both n-side and p-side InAs based unipolar barrier photodiodes with AlAs0.18Sb0.82 barriers, as well as conventional pn junction detectors. Numerical simulation was used to calculate the current-voltage (I-V) characteristic and R(0)A values for InAs unipolar barrier photodiodes and traditional pn junction photodiodes. The performances of different device structures have been investigated for temperatures from 150 K to 350 K. Comparing to conventional devices, the unipolar barrier device has shown significant performance improvement.