"Dressed photon" allows Si and SiC to emit light of various colors

"The beginning of development is incredible. The research team of nano photonic research center of the University of Tokyo Graduate School of engineering, Professor, director of Otsu Shimotochi after two years ago in 2011 to achieve high efficiency silicon light emitting, again let SiC and GaP luminescence (Figure 1). All of these semiconductors have indirect transfer band structure. In other words, when the conduction band electrons migrate to the valence band, the momentum conservation can not be achieved because of the general momentum, so they can not migrate. Therefore, the industry has always believed that these semiconductors are not suitable for the manufacture of light-emitting devices".

The p layer is formed at the same time of irradiation

The indirect transfer type semiconductor light is able to reason, the use of Dressed development lab "photon Otsu (dressed photon), can set up the band structure for previously unavailable migration" migration bridge "(Figure 2).

Dressed photon is refers to the fine particles (nanoparticles) irradiation of light, the photon and the nano particles of electronic combination, like "clothes" attached to the nanoparticles on the photon note 1).

Note 1) electronic and material on the surface of the photon and surface plasmon ", but" the difference between the two is the surface plasmon frequency, Dressed photon frequency is not fixed (Tianjin). According to Otsu introduction, the reason is very small nanoparticles, so the effect of the uncertainty principle is obvious. But, until recently, has been called the "Otsu near-field light", but "found in the course of the study, called the Dressed photon is more appropriate".

Electrons bound to the Dressed photons form discrete levels of energy (phonon energy levels). Ohtsu et al through the formation of energy levels in the semiconductor, electron mobility is realized.

The fabrication method of the luminescent silicon LED "Dressed photon reference annealing method" is as follows (Figure 3). When the p layer is made of silicon LED, the current is added to the silicon doped with boron (B), and it is annealed at 300 C for about 10 minutes by the Joule heating. At this time, the light from the external components. As a result, the boron particles which are irradiated by the light form the phonon energy level and the stimulated emission phenomenon occurs. After fabrication, the LED can emit light by injecting current without exposure to light.

The focus here is light exposure. If the light is not irradiated, the stimulated emission phenomenon will not occur, and LED will not emit light. The distribution of boron is "in the light of fractal distribution into spontaneous *" (leading the study in the Research Office of the Deputy Otsu distinguished professor of Sichuan Tim Chung). The emission wavelength can be changed by selecting the irradiation light. Longer than the band gap and shorter than the wavelength band gap can be. When the irradiation light is white, the white light LED can be made.

A structure that will appear in the same pattern or shape when magnified in detail by a particular pattern or shape.

Also contributed to improving the efficiency of solar cells

These semiconductors are widely used (Figure 4). One of them is silicon photonics which can only be used to realize optical transmission". Intel, IBM, Hitachi and NEC produced by the company are trying to find that the luminescence of silicon technology, technology has strong impact force. Otsu said, "there are a number of applications more interesting".

For example, the silicon LED can also be directly converted into a high efficiency solar cell that can be used to generate electricity with a wavelength longer than a gap or a short light. Otsu laboratory recently has started to verify this, has confirmed that the conversion efficiency of solar cells is improved by about two percentage points. Moreover, there is hope to achieve the same as the organic EL light-emitting inorganic material display.

Room is still in cooperation with enterprises on optical logic gate and the working principle and the existing computer different computer Otsu research.