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

Automated summary

Theoretical analysis demonstrates that the ultimate detectivities in multi-stage interband cascade infrared photodetector configurations can be higher than in conventional single-absorber structures, even with very long carrier diffusion lengths. Detailed derivations show that in the limit of infinite diffusion length, the detectivity of a multiple-stage device can be about 11% higher than that of an optimized single-stage device. Insight and explanations are provided to improve understanding and generate interest in the development of advanced multi-stage photodetectors.