According to the consulting report of Meymers, scientists at Rice University and Tokyo Metropolitan University in Japan observed a novel quantum effect in the carbon nanotube film. This quantum effect may contribute to the unique laser. And other optoelectronic devices R & D.
The 'Rice- Tokyo' research team reported that by using single-walled carbon nanotubes as plasmonic quantum confinement fields, the ability to manipulate light at the quantum scale has made significant progress.
This phenomenon was discovered by the physicist Junichiro Kono in the lab of Rice University of the United States. This may be a key technology for the development of nano-sized near-infrared lasers and other optoelectronic devices. The wavelength of the continuous beam emitted by the nano-near-infrared laser is too short to The current level of technology is not yet realized.
Nature Communications publishes a detailed description of this new study.
The Kono team found this method of 'very tightly-arranged carbon nanotubes in wafer-size films' that can achieve experiments that are difficult to achieve in single or entangled nanotube aggregates. This attracted the attention of Kazuhiro Yanagi, a physicist at Tokyo Metropolitan University. Yanagi specializes in condensed physics in nanomaterials. The two sides began joint research.
Kono introduced the cooperation project and said: 'In this research, Yanagi provided the 'gating technique' (this technology can control the density of electrons in the nanotube film). We provided the CNT alignment technology. This is the first time we have manufactured such a large-area regularly arranged carbon nanotube film with a 'gated gate' that allows us to inject and take out a large amount of free electrons.
Yanagi added: 'Gate control technology is very useful, but the carbon nanotubes in the membranes I used before are randomly arranged. This situation is very frustrating because I can't accurately know the nanotubes in this type of film. The one-dimensional nature of this, and this is actually very important. The film provided by the Kono team is very amazing, because these films can finally help me solve this problem.
The two teams combined the techniques to achieve the challenge of 'injecting electrons into nanotubes that are only 1 nanometer wide and then exciting them with polarized light'. The width of the carbon nanotubes captures the electrons in the quantum well, where atoms and sub- The energy of atomic particles is 'restricted' in a certain state or subband. Polarized light then causes them to oscillate rapidly between the tube walls. Kono thinks: 'As long as there are enough electrons, they can act as plasma.'
Kono said: 'The plasma is a kind of collective charge oscillation in a confined structure. For a plate, a piece of film, a ribbon, a particle or a sphere, if you disturb these systems (usually using a light beam), these free carriers will The eigenfrequencies collectively move. 'And this effect is determined by the number of electrons and the size and shape of the object.
In experiments at Rice University in the United States, because the nanotubes are so thin, the energy between the quantum sub-bands is almost equal to the energy of the plasma. Kono thinks: 'This is the quantum mechanism of plasmons, where the sub-bands The transition is known as the intersubband plasmon (ISP). Researchers have studied this phenomenon in artificial semiconductor quantum wells in the ultra-far infrared wavelength range, but this study is the first time natural occurrence occurs in low-dimensional materials. The phenomenon is observed under the condition of a short wavelength.
This very complex 'gate voltage dependence' detected in the plasmon response is a surprise, as it is in metal and semiconductor single-wall nanotubes. Kono believes: 'By researching light nanometers' Based on the basic theory of tube interaction, we can derive the formula for resonance energy. To our surprise, this formula is very simple. Only the nanotube diameter is the decisive variable.
The researchers believe that this phenomenon may promote the development of communications, spectroscopy, imaging, and highly adjustable near-infrared quantum cascade lasers.
The Kono team is a pioneering team that utilizes regularly arranged nanotubes for device development. Weilu Gao, a co-author of the study and a postdoctoral fellow of the Kono team, believes that traditional semiconductor lasers rely on the band gap width of laser materials, but quantum cascade lasers do not Weilu Gao said: 'The quantum cascade laser's wavelength is independent of the band gap. Our laser belongs to this class. We can tune the plasmon resonance energy only by changing the diameter of the nanotube, without considering the band. Gap problem. '
Kono also predicts that this kind of gridded, regularly arranged nanotube film will give physicists an opportunity to study Luttinger's theory of liquid interactions in one-dimensional conductors.
Kono thinks: 'One-dimensional metal prediction is very different from two-dimensional and three-dimensional metals. Carbon nanotubes are one of the best candidates for observing Luttinger's liquid behavior. Single nanotube research is quite difficult, but we have established a Macroscopic one-dimensional systems. Fermi energy can be adjusted by doping or gating. We can even convert one-dimensional semiconductors into one-dimensional metals. Therefore, this is an ideal system for studying such physical phenomena.
Yanagi, professor of condensed physics at Tokyo Metropolitan University, was the first author of the paper. The co-authors of the thesis include: Ryotaro Okada and Yota Ichinose from Tokyo Metropolitan University, Yohei Yomogida, a professional assistant professor, and Fumiya Katsutani, a graduate student from Rice University. Kono is Professor of Electronics and Computer Engineering/Physics and Astronomy/Materials Science and Nanoengineering.
The research was funded by the Japan Society for the Advancement of Science Research Grant (KAKENHI), Japan's Science and Technology Development Promotion Core Project, the Yamada Foundation for Science and the US Department of Energy's Basic Energy Science Project, the National Science Foundation and the Robert Welch Foundation. Funding.