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Photocurrent generation in semiconducting and metallic carbon nanotubes


The fundamental mechanism underlying photocurrent generation in carbon nanotubes1,2,3 has long been an open question. In photocurrent generation, the temperature of the photoexcited charge carriers determines the transport regime by which the electrons and holes are conducted through the nanotube. Here, we identify two different photocurrent mechanisms for metallic and semiconducting carbon nanotube devices with induced p–n junctions4,5,6,7. Our photocurrent measurements as a function of charge carrier doping demonstrate a thermal origin8,9 for metallic nanotubes, where photo-excited hot carriers give rise to a current. For semiconducting nanotubes we demonstrate a photovoltaic mechanism10,11,12, where a built-in electric field results in electron–hole separation. Our results provide an understanding of the photoresponse in carbon nanotubes, which is not only of fundamental interest but also of importance for designing carbon-based, high-efficiency photodetectors and energy-harvesting devices.

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Figure 1: SPCM and electrical characterization of semiconducting and metallic carbon nanotube devices.
Figure 2: Gate-dependent conductivity.
Figure 3: Photocurrent response for homogeneous doping.
Figure 4: Spatial photocurrent response.


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This research was supported by the Dutch Foundation for Fundamental Research on Matter (FOM). The authors would like to thank M.S. Rudner for discussions.

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M.B. fabricated the devices, performed the measurements and wrote the manuscript. V.Z. supervised the project. All authors discussed the results and commented on the manuscript.

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Correspondence to Maria Barkelid.

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The authors declare no competing financial interests.

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Barkelid, M., Zwiller, V. Photocurrent generation in semiconducting and metallic carbon nanotubes. Nature Photon 8, 47–51 (2014).

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