Ultimate detectivity of multiple-stage interband cascade infrared photodetectors

In this work, we theoretically demonstrate that the ultimate detectivities in multi-stage interband cascade infrared photodetector configurations are higher than what can be achieved a conventional single-absorber detector structure any circumstance even including where carrier diffusion length is very long. Detailed derivations provided to analytically show limit of an infinite length, detectivity multiple-stage device about 11% optimized single-stage device. Furthermore, how sequence absorber thicknesses for maximizing described and discussed. Insights explanations results presented improve understanding, clarify possible confusion with different perspectives technical community, generate more interest development advanced photodetectors various applications.