When Beijing is at night, if you have the opportunity to pass the North Fourth Ring Road by car, you will be attracted by the radiant, colorful bird's nest and water cube, and you can't help but stop to appreciate it.
Behind these Ambilight buildings, the main benefit is the full use of semiconductor lighting technology.
It is a pity that 440,000 sets of LED lighting equipment in Water Cube and about 258,000 sets of LED lighting equipment in Bird's Nest are purchased from CREE, which is difficult to find the trace of "domestic production".
In fact, with the third generation of semiconductor materials becoming the frontier and hotspot of global semiconductor research, China is catching up in key research fields such as semiconductor material light-emitting devices and microwave power devices, and even starting trial production and trial use. However, compared with foreign counterparts, The gap still exists.
"What is the biggest bottleneck? It is raw materials." Wang Xiaoliang, a researcher at the Institute of Semiconductors of the Chinese Academy of Sciences and secretary general of the Semiconductor and Integration Technology Branch of the Chinese Electronics Society, said that the quality and preparation of raw materials need to be solved urgently.
"Wide Band" has a bright future
The contemporary civilized society constructed by materials, information and energy is indispensable. Academicians of the Chinese Academy of Sciences and semiconductor physics experts Huang Kun and Xia Jianbai once pointed out that "semiconductors not only have extremely rich physical connotations, but also their performance can be placed under the constant development of precise process control", which can be described as the "most promising" material.
Compared with the second-generation semiconductor materials (represented by gallium arsenide and indium phosphide), wide bandgap semiconductor materials represented by gallium nitride (GaN) and silicon carbide (SiC) have high power density, small size, and high quality The light nature and broad application prospects are considered to be the third generation semiconductor materials.
"Especially in the fields of semiconductor lighting and microwave power devices, many countries are stepping up their deployment on the new generation of semiconductor materials, not to be left behind." Wang Xiaoliang said that semiconductor white light lighting is known as "the second lighting revolution after Edison invented the light bulb."
At present, the application range of semiconductor light-emitting devices is wide, covering almost all kinds of signal lights, interior lighting, information screens, color display devices, and even white light illumination.
Wu Ling, Secretary-General of the Technology Innovation Strategic Alliance for Semiconductor Lighting Industry, believes that in the next few years, China has the opportunity to become the world's semiconductor lighting industry power.
Wang Xiaoliang told reporters that the power density of gallium nitride is 10 to 30 times that of gallium arsenide; in addition, its extreme operating temperature is also relatively high, which weakens the problem of heat dissipation. The microwave power devices prepared with this material will be better used in key fields such as communications, radar, mobile phone base stations, information processing, and automation control.
"The application of microwave power devices is a strategic high ground for countries to compete for." Wang Xiaoliang said that these are very important whether in the military field or in the civilian market.
The new generation of power electronic devices made with wide-bandgap semiconductor materials have lower losses and higher efficiency, and are expected to play a role in the "smart grid" project. Wang Xiaoliang told reporters that a new generation of power electronic devices (such as power switches of gallium nitride and silicon carbide materials) will play an energy-saving role in all aspects of power generation, transmission, transformation, distribution, power consumption and dispatching of power systems. Reduce power consumption.
Opportunity to leapfrog development
"If we can seize the opportunities for the development of wide-bandgap semiconductor materials represented by nitrides, it will provide us with opportunities to achieve leapfrog development." Wang Xiaoliang said.
There is no doubt that China, as the world's largest producer and consumer of electronic products and equipment and the largest consumer of semiconductor materials, has achieved great strides in the development of semiconductor materials, which is of great strategic significance.
"During the rise and development, some Western countries have never ceased to harass our country and tried to contain our development. The suppression of military, economic, monetary and other aspects comes down to the competition of scientific and technological forces." Wang Xiaoliang said, only rely on Only with scientific and technological innovation can we have independent guarantees, and we will not be held back by forces with ulterior motives.
According to Wang Xiaoliang, the United States has developed the first gallium nitride materials and devices as early as 1993, and the earliest research team in China, the Institute of Semiconductors of the Chinese Academy of Sciences, also started research in this area in 1995, and started in 2000. Yearly made HEMT structure material (high electron mobility transistor).
Since then, the Institute of Semiconductors has made great achievements, and has jointly developed the first GaN-based HEMT device in China, the first GaN-based X-band microwave power device, the first GaN-based microwave monolithic integrated circuit, and so on.
After years of innovative research, China has gradually become the forefront of some researches. For example, the room temperature mobility of AlGaN / GaN structure developed by the Semiconductors of Chinese Academy of Sciences exceeds 2100cm2 / v · s, which is the world's leading level.
"Foreign countries are one step ahead of us, we admit the gap, but we must follow the scientific attitude of 'introduction-digestion-absorption-innovation", learn their advanced experience, save our resources and time costs, leapfrog development, and finally through independent innovation To achieve transcendence. "Wang Xiaoliang said.
Self-preparation faces difficulties
Wang Xiaoliang said that China is still facing difficulties in the independent preparation of the third generation semiconductor materials.
Zeng Jianping, an associate professor in the Department of Applied Physics of Hunan University, pointed out that the preparation of SiC wafers in China is still vacant. The materials for experiments are mostly from the United States. The preparation of new materials requires new production lines and new processes. The current situation is that China Most of the equipment is imported from abroad.
The MOCVD system is a necessary equipment for the production of heterostructure materials for LED epitaxial wafers and microwave power. With the continuous expansion of the compound semiconductor device market, the demand for MOCVD systems continues to grow, and China is almost entirely dependent on imports.
It is understood that the main international MOCVD equipment suppliers-German AIXTRON company and the US VEECO company-quotation for a single MOCVD equipment up to 20 million yuan, while China purchased dozens of units in 2012, the cost is staggering .
Even so, key equipment like the MOCVD system, which involves defense technology, is difficult to obtain optimal performance even if it is imported. "Can foreign countries sell the best equipment to you casually?" Wang Xiaoliang asked rhetorically.
It is reported that since the 1980s, the road to localization of China's MOCVD equipment has not been smooth. So far, China's MOCVD equipment is still in the engineering prototype stage. It is currently only used for scientific research and there is no MOCVD equipment that can be used for mature industrial production. factory.
"The display of the material itself is not large, and people's attention to the material is easily weakened." Wang Xiaoliang believes that one of the reasons for the debt in the preparation of the material is that the material has not received the attention it deserves.
"Materials are located in the upstream of the industrial chain. If you do not pay enough attention to the materials, midstream devices and circuits and downstream systems can be imagined." Wang Xiaoliang said that the output of the downstream of the industrial chain should be based on upstream materials. In fact, China There is not enough attention to the basic material issues; once the investment and support are not enough, the relevant talents will be difficult to be attracted, and the problem of talent team construction will gradually become a bottleneck in development.
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