Single Nanotubes Yield IR Radiation

Researchers at the IBM Thomas J. Watson Research Center in Yorktown Heights, N.Y., have reported the emission of electrically driven polarized infrared radiation from ambipolar field-effect transistors consisting of single or bundled semiconducting single-walled carbon nanotubes. They reported the development, which has potential applications in the production of ultrasmall photonic devices, in the May 2 issue of Science.

To fabricate the emitters, they deposited the approximately 1.4-nm-diameter nanotubes from solution onto a P-type silicon substrate covered with a layer of silicon dioxide. Titanium source and drain electrodes were built atop individual nanotubes, and a 10-nm-thick layer of silicon dioxide capped the structures. Although the devices produced radiation just outside the L-band at approximately 1650 nm, the wavelength of the emission should be controllable by employing nanotubes of different diameters.