Special Section on Infrared Sensors

Theoretical analysis of nBn infrared photodetectors

[+] Author Affiliations
David Z. Ting, Alexander Soibel, Arezou Khoshakhlagh, Sarath D. Gunapala

NASA Jet Propulsion Laboratory, California Institute of Technology, Center for Infrared Photodetectors, Pasadena, California, United States

Opt. Eng. 56(9), 091606 (Feb 10, 2017). doi:10.1117/1.OE.56.9.091606
History: Received November 7, 2016; Accepted January 25, 2017
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Abstract.  The depletion and surface leakage dark current suppression properties of unipolar barrier device architectures such as the nBn have been highly beneficial for III–V semiconductor-based infrared detectors. Using a one-dimensional drift-diffusion model, we theoretically examine the effects of contact doping, minority carrier lifetime, and absorber doping on the dark current characteristics of nBn detectors to explore some basic aspects of their operation. We found that in a properly designed nBn detector with highly doped excluding contacts the minority carriers are extracted to nonequilibrium levels under reverse bias in the same manner as the high operating temperature (HOT) detector structure. Longer absorber Shockley–Read–Hall (SRH) lifetimes result in lower diffusion and depletion dark currents. Higher absorber doping can also lead to lower diffusion and depletion dark currents, but the benefit should be weighted against the possibility of reduced diffusion length due to shortened SRH lifetime. We also briefly examined nBn structures with unintended minority carrier blocking barriers due to excessive n-doping in the unipolar electron barrier, or due to a positive valence band offset between the barrier and the absorber. Both types of hole blocking structures lead to higher turn-on bias, although barrier n-doping could help suppress depletion dark current.

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© 2017 Society of Photo-Optical Instrumentation Engineers

Citation

David Z. Ting ; Alexander Soibel ; Arezou Khoshakhlagh and Sarath D. Gunapala
"Theoretical analysis of nBn infrared photodetectors", Opt. Eng. 56(9), 091606 (Feb 10, 2017). ; http://dx.doi.org/10.1117/1.OE.56.9.091606


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