IBM and Duke University, U.S. researchers have succeeded in single-wall carbon nanotubes (single-walled carbon nanotube), issued by high-intensity infrared light. They make carbon nanotubes a part of the suspension on the silica substrate, and single-carrier operation (unipolar operation), the results of the carbon nanotube suspended and the junction formed by the support given at the high brightness of the infrared light.
Researchers using chemical vapor deposition (chemical vapour deposition), the diameter of 2 ~ 3 nm carbon nanotubes cross carved grooves on (trench) of the silica substrate, a part of carbon management across the groove at the top, then add Pd (palladium) as the source and drain, in the single-carrier transport conditions (ie less than about -3.1 V gate voltage will lead to hole transport, the gate voltage greater than -2.1 V lead to electronic transmission), carbon nanotubes are suspended part of the substrate supporting the formation of the junction with the Department will send out infrared light, the luminous efficiency leads to 3 μA current was about 107 per square nanometer photons per second, than the current large LED area 105 times higher.
Researchers believe the reason light-emitting carbon nanotubes, carbon nanotubes that are supported by most of the junction with the vacant near the band of carbon nanotubes will bend, the resulting electric field will accelerate the carrier, and thus generate excitons (exciton, ie Bound pairs of electron and hole); When the electron - hole pair recombination time will be light. According to the researchers calculated the efficiency of this approach is to stimulate, respectively, electrons and holes injected from both ends of the recombination efficiency of more than 1,000 times.
This study demonstrated that in low-dimensional nano-structure, the electron and hole has a very strong attraction, and carrier and the coupling between atomic vibrations is very weak, but it also the first to show in the one-dimensional systems, molecular heat carrier (energy carrier) impact excitation (impact excitation) phenomenon.
Because carbon nanotubes are issued 1-2 μm wavelength infrared light, so it has applications in optical communication on the potential, while the emission wavelength by changing the carbon nanotube diameter can be adjusted. In addition, the future of these carbon nanotube emitters can with the same or a carbon tube made of silicon electronic components integrated on a chip, a new electronic or optoelectronic components. .
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