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arXiv · 2112.11987

Sub-ns intrinsic response time of PbS nanocrystal IR-photodetectors

Andre Maier·Fabian Strauß·Pia Kohlschreiber·Christine Schedel·Kai Braun·Marcus Scheele
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Abstract

Colloidal nanocrystals (NCs), especially lead sulfide NCs, are promising candidates for solution-processed next-generation photodetectors with high-speed operation frequencies. However, the intrinsic response time of PbS-NC photodetectors, which is the material-specific physical limit, is still elusive, as the reported response times are typically limited by the device geometry. Here, we use the two-pulse coincidence photoresponse technique to identify the intrinsic response time of 1,2-ethanedithiol-functionalized PbS-NC photodetectors after fs-pulsed 1560 nm excitation. We obtain an intrinsic response time of ~1 ns, indicating an intrinsic bandwidth of ~0.55 GHz as the material-specific limit. Examination of the dependence on laser power, gating, bias, temperature, channel length and environmental conditions suggest that Auger recombination, assisted by NC-surface defects, is the dominant mechanism. Accordingly, the intrinsic response time might further be tuned by specifically controlling the ligand coverage and trap states. Thus, PbS-NC photodetectors are feasible for gigahertz optical communication in the third telecommunication window.

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Andre Maier, Fabian Strauß, Pia Kohlschreiber, Christine Schedel, Kai Braun, Marcus Scheele. 2021-12-22. Sub-ns intrinsic response time of PbS nanocrystal IR-photodetectors. https://doi.org/10.1021/acs.nanolett.1c04938

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