Details

Autor(en) / Beteiligte

• Sharma, Asha
• Singh, Virendra
• Bougher, Thomas L.
• Cola, Baratunde A.

Titel

A carbon nanotube optical rectenna

Ist Teil von

• Nature nanotechnology, 2015-12, Vol.10 (12), p.1027-1032

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A metal–insulator–metal architecture in which one metal is replaced by vertically aligned carbon nanotube antennae is used to convert light into direct current. An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current—was first proposed over 40 years ago 1 , yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale 2 , 3 . Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads 3 , 4 , but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna 2 . Here we demonstrate an optical rectenna by engineering metal–insulator–metal tunnel diodes, with a junction capacitance of ∼2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (∼10 nm in diameter), which act as the antenna 5 , 6 . Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna 7 , 8 , a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory 4 , 9 , 10 . Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current–voltage scans between 5 and 77 °C, indicating a potential for robust operation.