The three primary colors of light are red, green and blue. In other words, the three colors of light after mixing, can produce white light. After the red led was invented, in order to enable the led to achieve commercial, the invention of green and blue led became the focus of research scientists.
For the large-scale use of led to lay the most important piece of cornerstone is the Japanese scientists Amano Hao, Stanley Yong and the village of two. In 2014, they won the Nobel Prize in Physics for inventing blue LEDs, the blue led.
On the afternoon of March 11, Professor Amano at the University of Nagoya held a speech at the Shanghai Science Hall, sharing his experience of discovering blue LEDs and the current status and prospects of LED applications.
Compared with other scientists dedicated to discovering blue LEDs at the time, Amano and his mentor, Stanley Yong, chose a less-favoured compound as a research direction. He laughs that it may be a blessing to win the race on a shoestring, but it is hard to imagine.
"At that time, I was not particularly aware of how difficult this study, the first to study the LED display, is to facilitate the world, based on this idea to persist." ”
There are many lectures on the scene from Fudan, Tongji, Jiaotong University students majoring in physics, Amano's final warning earnestness, "If you have hesitation in the research process, I hope you can return to your dream of starting point, think of why you do this research." ”
Blue LEDs become the focus of research
At first, the research direction was not promising.
In the 20th century, the main use of human lighting is incandescent lamps. The lighting tool, invented by Edison at the end of 19th century, is the principle of heating the filament to an incandescent state, using thermal radiation to emit visible light. It can be imagined that in the process of incandescent light, a large part of the energy has become heat dissipation, loss is very serious.
The American scientists invented the red led in the 1960 's. Compared with incandescent lamp, LED light-emitting diode has low voltage, small current and high luminous efficiency, which becomes a hotspot of new generation illumination.
1974, Green LED was developed. After that, the researchers focused on the blue LEDs on silicon carbide (sic), zinc selenide (ZnSe) and gallium nitride (Gan).
Many people had failed after attempting to gallium nitride, looking to the other two materials that seemed more promising.
But some people have not lost confidence, that is, the teacher of Amano Hao Professor Chi Yong. Red Qi Yong At that time in the enterprise to do research, gallium nitride is not a blue LED research hot, many people advised him not to do this aspect of research, Chi Yong to the study transferred to the University of Nagoya. 1982, Amano University after graduating into the Red Qi Yong Studio, began to contact the blue led research and development work.
In an unpopular material input, no funds are not optimistic, this research road at the beginning of the doomed rugged, but Amano did not care, but a headlong into a hard study.
"I sometimes feel that this is also a kind of luck, in this direction in the end there is no one to compete with you, to concentrate on research." ”
LED lighting is possible after the invention of blue LED
Days Wild Hao memory, at that time, blue led research and development has three major difficulties: first, can not form high quality gallium nitride crystallization, the second is not to make gallium nitride P-type junction, the third is to create a high illumination of gallium nitride crystals.
"I was thinking that if the blue led could be successful, it would create a new display that could change the world," he said. Amano said that he started the study, initially holding the idea of benefiting the world.
After entering the Stanley-Yong Studio, Amano and other students followed the research work of the Chi-yong into gallium nitride.
The research was very difficult at the time, and they needed an experimental device priced at about 100 million yen, but the studio was only 2.7 million to 3.1 million yen. In order to carry out the research, the students together to discuss their own experimental equipment, using various "soil methods" to overcome difficulties.
Amano showed a photo of an experimental device they made, "it's important to have a beer bottle in the picture." The experiment heats the coil, and the size of the coil is equal to the diameter of the beer bottle, we make the coil around the beer bottle. ”
Amano Undergraduate 3 years, Master's 2 years have been invested in gallium nitride research, but did not see the synthesis hope. The family did not support his "dead knock" research, has stopped his tuition, fortunately he won a scholarship, it is possible to continue the doctoral program.
In the last year of Master's degree, Amano was inspired by a teacher in a discussion, thinking of making a cryogenic buffer layer on a sapphire substrate and then making a gallium nitride crystal on it. It is proved that this method can be made into gallium nitride crystallization with high crystallinity, and the realization of this high quality gallium nitride single crystal is regarded as one of the "breakthrough technologies" of blue led invention.
Thereafter, during the days of Dr. Amano, Chi-Yong Studio successfully made a P-shaped knot. On the basis of these studies, in 1993, China Village repair two successfully invented the high-brightness blue led, led in the lighting and display on the application is possible.
How much contribution the LED can make to energy saving
How much contribution can the LED make to saving energy? Amano said, according to the relevant statistics, if the national wide-spread LED lighting in Japan, can save 7%.
This power-saving, portable lighting is also a great help in protecting local culture. Mongolia also has a lot of people to maintain the nomadic habits, no stable power supply, led the popularization of their lighting has a great guarantee, but also in tents to watch TV.
"I am very happy to hear that." LEDs can illuminate 1.5 billion people in the world without infrastructure. "Amano said.
In addition to LED lighting and display, the crystallization of gallium nitride has been used in other aspects of energy conservation.
The drive motor uses more power than lighting. Japan on the motor 100% using inverter to achieve electricity-saving purposes. But the inverter in the process of converting DC power into alternating current, there will be about 5% of the energy loss, after many conversions, about One-fourth of the energy will be lost.
Amano said that the inverter will be silicon this semiconductor material to gallium nitride, size can do one-tenth of the silicon, loss can also be reduced to the original one-tenth. Research from the University of Nagoya confirms that this method can save 10% of electricity in Japan.
Regarding the future society, the Japanese cabinet house envisages is "the Ultra Intelligent Society", is uses the big data way to process the data real-time and the real-time feedback, "the massive information transmission needs to raise the frequency, can increase the transmission frequency is also the gallium nitride material." ”
In addition, Amano is also involved in the development of deep ultraviolet led, the LED is also made of gallium nitride raw materials. The killing of E. coli reached 99.9%.
According to UN statistics, 663 million people around the world cannot use safe drinking water, and 2.4 billion people do not have access to sanitary toilets. UV LEDs can contribute to the use of clean water for these people. ”
"The purpose of scientific research should be to benefit people all over the world"
Nobel Prize issued a certain lag, a study of the results of the time to prove its value will be the Nobel affirmation.
In the 21 years after the blue led was invented, LED was used extensively as a new type of energy. 2014, Chi Yong, Amano, Nakamura two because of the contribution on the blue led to share the Nobel Prize in physics. "The advent of Blu-ray LED allows us to create white light in a completely new way," the award word says. With the birth of LED lights, we have a more durable, more efficient new technology to replace the old light source. ”
Amano said he won the Nobel Prize is completely unexpected, he was released from Nagoya to Frankfurt, even without paying attention to this matter. A lot of the Japanese get the news waiting for him at the airport, out of the airport Amano think they are waiting for an entertainer, completely improper to go back to the matter, the result was a reporter called Live.
"This is the first time I've heard of my own prize. ”
Amano said that the award is very happy things, but no researcher is for the award and research. Their student period, 365 days a year 364 days in the laboratory, only New Year's Day at home. Do research from 10 in the morning to two or three in the middle of the night, in addition to eating does not stop, "there is no time to do other things, is not to do, because research is too fun." ”
He has repeatedly mentioned that scientific researchers do research work in order to benefit people all over the world. "It has been reported recently that the 8 richest people in the world account for roughly half the wealth of the world's poor, and that scientific research does not work for such people," I firmly believe. Recently, terrorism has often been a topic, and the Gini coefficient has changed dramatically in the 1980, and I believe that technology and science are the best tools to eliminate this bad phenomenon. ”
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