LED semiconductor lighting network third-generation semiconductor materials mainly include gallium nitride (Gallium Nitride, GaN), silicon carbide (SiC), zinc oxide (Zinc Oxide, ZnO), aluminum nitride (Aluminum Nitride, AlN) and Wide band gap semiconductor material such as diamond. Compared with semiconductor materials such as silicon (Silicon, Si) and GaAs, the third-generation semiconductor materials have a large band gap and have superior properties such as high breakdown electric field, high thermal conductivity, and high electron saturation rate. Among them, nitride materials are the most attractive materials in the third generation of semiconductor materials, especially GaN (gallium nitride) based optoelectronic devices are very successful in the field of white light illumination. However, the technical patents for blue LEDs (light-emitting diodes) are subject to earlier countries such as Europe, the United States and Japan. Therefore, the ultraviolet LED based on AlGaN (aluminum gallium nitride) material in the early stage of development has become the best field to break through the patent monopoly. In addition, UV LED is also the main trend of the development of nitride technology and the development of third-generation material technology, and has broad application prospects.

At present, the global UV light source market is about 427 million US dollars, but the traditional ultraviolet mercury lamp still dominates the market. Compared with mercury lamps, the rapidly developing ultraviolet LED light source in recent years is recognized as having eight advantages. First, it is small in size and has great potential in portable, highly integrated products. The second is rugged and durable. The LED is more resistant to impact than the mercury lamp in the quartz glass case and is less prone to damage. Third, the energy efficiency is high. Compared with mercury lamps, the energy consumption of ultraviolet LEDs can be as low as 70%. The fourth is environmental protection, UV LED does not contain harmful substances mercury, passed ROHS certification. Fifth, the working voltage is low, and the operating voltage of the ultraviolet LED is only about 3-5 volts. Compared with the high pressure mercury lamp, the safety is improved and the cost of the driving circuit is reduced. Sixth, the power is easier to adjust. Seventh, the cooling system requirements are low, further reducing system cost. Eighth, the optical system is simple and more suitable for practical applications. The UV LED can obtain a compact beam angle and a uniform beam pattern without an external lens, thereby reducing cost and enhancing system reliability. Because of these advantages, UV LED technology is becoming an attractive option for the solid-state UV light source industry.

At the same time, compared with the traditional ultraviolet light source mercury vapor lamp and excimer laser, the solid-state ultraviolet light source has many advantages such as small and portable, green and environmental protection, easy wavelength tuning, low voltage, low power consumption, integration, etc. With the continuous advancement of technology, Will become the mainstream of the future UV light source. In information optical storage, the data density is determined by the wavelength of the source of the read and write. Deep-UV laser diodes are expected to increase information capacity by tens of times compared to blue-ray laser-based blue-ray technology due to extremely short wavelengths. In biochemical analysis, most biomolecules contain chemical bonds with strong optical resonance in the ultraviolet (270-350 nm) band. Small and efficient UV sources can provide a bridge between bioprobe and optoelectronics, enabling biophotonics. Applications are possible, such as fluorescence-based bioagent recognition; optical detection is also an extremely efficient method for studying protein structure, and optically excited two important amino acids, tryptophan and tyrosine, require a 275 nm UV source. Deep-UV LEDs are ideal new-generation light sources with huge market potential and will play an important role in intelligent manufacturing and improving people's quality of life.

In order to accelerate the development of the third-generation semiconductor solid-state ultraviolet light source in China, the Ministry of Science and Technology has implemented a special research and development plan to carry out research work on the third-generation semiconductor solid-state ultraviolet light source materials and key technologies of devices. The project is led by the Institute of Semiconductors of the Chinese Academy of Sciences, and has assembled the leading institutes, universities and industry leading and application enterprises in the field of the third-generation semiconductor solid-state ultraviolet light source in China, and concentrated on professional technical forces to carry out technical research on solid-state ultraviolet light sources, with a view to 5 - In 10 years, catch up with the international advanced level, and at the same time realize the market-oriented application of the third-generation semiconductor solid-state ultraviolet light source as soon as possible, and promote the development of the market, and drive the development of the third-generation semiconductor solid-state ultraviolet light source related industry in China.

The Institute of Semiconductors of the Chinese Academy of Sciences is one of the earliest units in China to conduct research on nitride materials, and has undertaken and completed many major national research tasks. During the “Eleventh Five-Year Plan” period, the project leader undertook the National 863 Frontier Exploration Project “Research on the Growth of AlGaN Materials for Ultraviolet LEDs”, which realized the first milliwatt optical power output of deep ultraviolet LED devices with a wavelength shorter than 300nm in China. The 11th Five-Year Plan 863 plans new research areas highlights, and received further support from the “11th Five-Year” Phase II national project, undertaking the 863 project “Deep UV LED Preparation and Application Technology Research”, MOCVD epitaxial technology based on AlN template A series of achievements have been made to nearly double the performance of deep ultraviolet LEDs. The “Twelfth Five-Year Plan” undertakes the “Deep Ultraviolet LED Epitaxial Growth and Applied Technology Research” of the National 863 Project, and the results have been certified by the expert group to reach the domestic leading and international advanced level. At present, he is responsible for the 863 project "Research on the preparation technology of high-aluminum component nitride materials", and for the first time in China, the optical pump lasing of semiconductor lasers with room temperature near gamma 377nm and deep ultraviolet 288nm is realized.

This project is in line with the previous research projects of deep ultraviolet LED, and has shifted from the early stage of the cutting-edge technology exploration stage to the common key technology breakthrough stage. The comprehensive index of materials and devices of semiconductors has always maintained the best level in China. The quality of high-alloy component materials is at the best level in the world. The first deep-UV milliwatt-class LEDs in China have been developed and the efficiency is always leading. For the first time, the blue laser has achieved the optical pump lasing of the laser near room temperature 377nm and deep ultraviolet 288nm, maintaining the leading edge of the violet laser; the related results won the "National Technology Invention Second Prize" and the "National Science and Technology Progress Second Prize" "1 item, "First Prize of Beijing Science and Technology Progress Award". Provided a solid technical guarantee for the smooth implementation of the project.

Research firm Yole Development released the latest market research report in February 2015. The market will break the calm after 2015 and begin to accelerate growth. It will grow by leaps and bounds in 2018, and the agency believes that the first round of growth in the driving industry The main factor is the light curing application that started in 2012. The general trend of UV-LED replacing mercury lamps is the main driving force of this round of growth, and the application in the field of sterilization and purification will become the second driving force of industrial growth. A round of growth will begin in 2017. In the near future, photocatalysis, sterilization and disinfection are likely to grow into tens of billions of markets, and phototherapy for the treatment of skin diseases may make the UV-LED application system a billion-dollar market.

In combination with the international development trend of semiconductor ultraviolet solid-state light source research, through the implementation of this project, relying on our existing work basis and advantages, the system research on the epitaxial growth, device preparation and packaging process of AlGaN-based deep ultraviolet LED structure. The scientific significance of this project is to establish relevant high-al-component material mechanism theory and original technology innovation system from the national economic, social development and national defense safety to the significant demand of the third-generation semiconductor solid-state ultraviolet light source materials and devices, and to overcome a series of related Key technologies, access to high-quality materials, development of high-performance devices, development of related products and application demonstration. At the same time, it has nurtured and condensed a research team with international level to lay an important scientific foundation for the important application of III-type nitride semiconductor ultraviolet LED in the fields of air and water purification and other sterilization, and it is related to national security and promotion. Contribute to the development of the technology industry.

Specifically, the development of domestic solid-state ultraviolet light source manufacturing equipment can be promoted first. At present, there is no mature commercial equipment for the manufacture of ultraviolet light sources at home and abroad. It can be said that everyone is at the same starting line, and any breakthrough in technology will bring about tremendous development of the industry. By developing high-temperature MOCVD equipment manufacturing technology, it can drive the development of domestic basic manufacturing.

Secondly, it can promote the development of upstream enterprises such as materials and chips. At present, the upstream enterprises of blue LEDs are in a state of saturation. Through the development of ultraviolet light sources, the transformation and upgrading of upstream LED enterprises can be promoted, and the development of domestic high-tech industries will be promoted.

Finally, through the application of product development, it can promote the development of downstream application enterprises such as domestic packaging and applications. Utilizing the bactericidal effect of UV LEDs, it can be widely used in white goods, such as refrigerators, air conditioners, washing machines, air purifiers, water dispensers, etc., which will be sterilized by ultraviolet LEDs. The sterilization function in these products will become products. Standard features. Only China's refrigerators, air conditioners, washing machines, air purifiers, water dispensers and other products, each product production and sales of tens of millions, or even hundreds of millions of units per year. According to statistics, in 2013, the total output of refrigerators, washing machines, air conditioners, air purifiers and water dispensers in China was 306.86 million units. If UV LED lamps are used in these products for sterilization, it will be a broad application market. The replacement of these original markets and the application of new market applications will greatly improve people's living standards, anytime, anywhere. Provide clean air, clean water, and improve the living environment for more people to enjoy health. At the same time, LED's long industrial chain and talent-intensive features will also generate tens of thousands of employment opportunities, have a positive impact on society, and obtain good social benefits.

The implementation of the key research and development plan for the “third-generation semiconductor solid-state UV light source materials and key technologies of devices” is one of the important changes in the national science and technology system reform. By focusing on the most advantageous teams in the country to carry out technical research, the key points are highlighted. Domestic technological innovation and technological breakthroughs.

Author: Institute of Semiconductors, Sun Lili, Wei Xuecheng, Yan Jianchang, Wang Junxi, Chinese Academy of Sciences, Chinese Academy of semiconductor lighting R & D center