| STUDY |
IBM scientists have generated an electrical current in a single carbon nanotube by shining light on it [Nano Lett., published online June 25, http://dx.doi.org/10.1021/nl034313e]. The finding, which helps to lay the groundwork for carbon- nanotube-based optoelectronics, follows a report published earlier this year in which the reverse process was observed. By developing the means to control light and electrical current on ever finer scales, scientists aim to produce tiny and sophisticated optoelectronic devices. Working toward that end, a research team at IBM's T. J. Watson Research Center, Yorktown Heights, N.Y., has devised a procedure for measuring electrical current generated by shining light on a single carbon nanotube. To make the measurements, the team--which includes Phaedon Avouris, Marcus Freitag, Richard Martel, and coworkers--constructed a field-effect transistor (FET) in which a single carbon nanotube serves as the semiconducting channel. The FET was designed to conduct positive and negative charge carriers (holes and electrons, respectively). Shining infrared light on the nanotube causes excitations that lead to electron-hole pairs, the team reports. By applying voltages to the device while irradiating it, the group was able to separate the charge carriers and investigate the dependence of electrical current on the frequency of the light and applied voltage. The measurements show that the device can serve as a nanoscale photodetector. The same setup was used by the IBM team recently to measure electrically driven light emission from a single carbon nanotube (C&EN, May 5, page 9). In that investigation, the team applied certain voltages to the device, injected positive and negative charge carriers, and observed light emission as the charge carriers recombined |
| UPDATE | 07.03 |
| AUTHOR | IBM's team--which includes Phaedon Avouris, Marcus Freitag, Richard Martel |
| LITERATURE REF. | [Nano Lett., published online June 25, http://dx.doi.org/10.1021/nl034313e]. |
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