Saturday, November 26, 2005

"Bright Infrared Emission from Electrically Induced Excitons in Carbon Nanotubes"


Nanotube films as shock absorbers, nanotubes as infrared emitters, these things are a technological explosion! I'm fascinated, but can't hope to keep up with the field.

"Bright Infrared Emission from Electrically Induced Excitons in Carbon Nanotubes
Jia Chen,1* Vasili Perebeinos,1 Marcus Freitag,1 James Tsang,1 Qiang Fu,2 Jie Liu,2 Phaedon Avouris1*
We used the high local electric fields at the junction between the suspended and supported parts of a single carbon nanotube molecule to produce unusually bright infrared emission under unipolar operation. Carriers were accelerated by band-bending at the suspension interface, and they created excitons that radiatively recombined. This excitation mechanism is 1000 times more efficient than recombination of independently injected electrons and holes, and it results from weak electron-phonon scattering and strong electron-hole binding caused by one-dimensional confinement. The ensuing high excitation density allows us to observe emission from higher excited states not seen by photoexcitation. The excitation mechanism of these states was analyzed.
1 IBM Research Division, Thomas J. Watson Research Center, Post Office Box 218, Yorktown Heights, NY 10598, USA.
2 Department of Chemistry, Duke University, Durham, NC 27708, USA. "