In recent years, the commercialization of third-generation semiconductor devices such as Gan and SiC has progressed well. While third-generation semiconductors are making progress on the road to commercialization, fourth-generation semiconductor materials have also made great strides. Compared with silicon-based and third-generation semiconductor materials, ultra-wide bandgap materials have advantages. Compared with the third-generation semiconductor materials, the fourth-generation semiconductor materials have some new improvements in voltage resistance and frequency performance.

In recent years, the commercialization of third-generation semiconductor devices such as Gan and SiC has progressed well. Gan devices are starting to be used for fast charging on a large scale, and SiC devices are also appearing in cars. Now we are very optimistic about the prospects of third-generation semiconductor equipment, and many companies have also entered the third-generation semiconductor industry.

While third-generation semiconductors are making progress on the road to commercialization, fourth-generation semiconductor materials have also made great strides. Not long ago, Professor Zhang Jie, Executive Dean of the School of Electronic Engineering of Beijing University of Posts and Telecommunications, shared the "Ultra Wide Bandgap Semiconductors for Carbon Neutral Development Summit" held at the same time as the 16th China Core Integrated Circuit Industry Promotion Conference in 2021 . Research Report on Semiconductor Gallium Oxide Materials and Devices.

He said in the report that gallium oxide is the fourth-generation semiconductor material B32-1630, which has received extensive international attention and recognition and is the best material for solar-blind optoelectronic devices. He introduced the advantages and development process of gallium oxide materials and the achievements of Beiyou in the research of gallium oxide materials.

Advantages of Gallium Oxide Materials

In the post-Moore era, wide-bandgap semiconductor materials with innate performance advantages stand out, increasing efficiency, density, size, weight, and overall cost. The width of the ultra-wide bandgap determines the withstand voltage, loss, power, frequency and usage. Compared with silicon-based and third-generation semiconductor materials, ultra-wide bandgap materials have advantages.

Typical materials of fourth-generation semiconductors are gallium oxide, diamond, etc. According to Professor Zhang Jie, Nordic has been researching gallium oxide materials for a long time. Gallium oxide semiconductor material is a representative material of next-generation ultra-wide band gap, and has been widely concerned and recognized in the world.

At present, the research and development of fourth-generation semiconductor materials has entered the international research field. Compared with the third-generation semiconductor materials, the fourth-generation semiconductor materials have some new improvements in voltage resistance and frequency performance. In addition, according to the annual academic statistics of relevant research topics by internationally renowned publishing groups, gallium oxide research has entered the frontier physics research of Keruivian in 2021, and has been promoted in the research.

In Professor Zhang Jie's view, gallium oxide material will play a very important role in the application of power electronic equipment in the future, because gallium oxide can reduce the electrical resistance by 7 times and reduce the loss by 86%, which can meet the high voltage and conductivity density of power semiconductor equipment. High, low conduction voltage, short switching time, low loss, very suitable for power electronic equipment applications.

In addition, the performance of gallium oxide material is also very strong. The band gap width is 4.9ev, the breakdown field strength is 8mv/cm, the Baliga figure of merit is 3214, and the conduction resistance is also very low. More importantly, once mass-produced, the cost of gallium oxide is only 1/3 of the average cost of third-generation semiconductor materials, which has more cost advantages.

Another application of gallium oxide material is in optoelectronic devices that take advantage of its ultra-wide bandgap properties. That is, it is mainly used in solar-blind optoelectronic devices, that is, in the ultraviolet region, wavelength, and forbidden bandwidth. Because solar-blind ultraviolet technology has important strategic significance in the fields of national defense such as infrared and ultraviolet two-color guidance, missile identification and tracking, and shipborne communication. Of course, in addition to national defense, this technology also has very important applications in the fields of people's livelihood such as power grid security monitoring, medical imaging, maritime search, environmental and biochemical detection.

Development of Gallium Oxide

Compared with third-generation semiconductor materials such as gallium nitride and silicon carbide, the research level of gallium oxide materials is relatively backward. At present, gallium oxide materials are mainly in the stage of experimental research and small-scale commercial supply. But its prospects are still good. First of all, its element reserves are relatively abundant, and its performance, energy consumption and future production are all good. At present, its industrialization is relatively easy.

Japan first began to study gallium oxide materials. In 2011, it began to vigorously develop technical research related to gallium oxide. At present, the level of commercialization in Japan is also the best. In 2018, the United States also began to study gallium oxide materials. China is also paying more and more attention to materials. In the 14th Five-Year Plan, the third-generation semiconductor materials are the focus of development, and ultra-wide bandgap semiconductor materials are included in the strategic research layout of the science and technology plan. In 2018, China also launched the exploration and research of ultra-wide bandgap semiconductor materials, including gallium oxide, diamond and boron nitride. Currently, Japan is a leader in gallium oxide research. Japan's Tamura is the first company in the world to develop gallium oxide single crystals, and has developed UVLEDs and UV detectors. Professor Zhang Jie said that only Tamura has gallium oxide single crystal substrates for research in the world. In addition, according to public data, Tamura in 2017 -ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title ="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title=" 2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model ">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model"> 2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017-ic/" title="2017 model">2017 Japan Hi-Tech Expo launched a gallium oxide power device.

As for the industrialization progress of gallium oxide materials, it is first necessary to make material substrates and single crystal production. At present, the single crystal preparation methods of gallium oxide include floating zone method (FZ), guided mode method (EFG), pulling method (CZ) and vertical bridgeman method (VB). Research on the preparation of single crystals has already started in the world, but they are all small-scale experimental applications. There are two popular routes, the guided mode method and the pulling method. Based on the practice in recent years, we realized that the yield of the guided mode method can meet the business requirements. Most companies use this technical route to manufacture single crystals. This technique is used in a 2-inch gallium oxide single crystal commercially supplied by Tamura. In 2016, Tamura also produced 6-inch single crystals, but has not yet achieved volume supply. Different universities and institutions in China are also carrying out related research work. At the end of 2019, Beiyou successfully achieved 3-inch single crystal guided mode growth.

The ultimate goal of preparing single crystals is to produce various equipment, and some progress has been made in equipment. Power devices produced from gallium oxide materials will have higher withstand voltage values that can exceed the physical limits of silicon carbide and gallium nitride. In the end, Prof. Zhang Jie also introduced the progress of Beiyou in the research of gallium oxide materials and equipment. According to him, Beiyou has a National Key Laboratory of Information Photonics and Optical Communication, where a research team focuses on the research of gallium oxide materials and devices. The person in charge is Professor Tang Weihua. He has worked in the field of gallium oxide for 11 years, focusing on solving the technical difficulties of material growth such as high corrosiveness, high volatility and ease of management, and multi-phase intergrowth, so as to meet the good uniformity of single crystal materials. Professor Zhang Jie said that the team not only studied gallium oxide materials and equipment, but also the preparation equipment of gallium oxide single crystal materials. At present, in terms of equipment, gallium oxide-based solar-blind UV detectors and array imaging equipment have been manufactured; gallium oxide-based Schottky diodes have also been manufactured, achieving 2 milliohms in the next two or three years.

Epilogue

At present, gallium oxide materials may not be commercial materials in the mainstream market, but from the current research, gallium oxide materials have shown some good performance in high-power, high-efficiency electronic equipment and laboratories, so they will be widely used in the future. Among them, gallium oxide may have good application prospects, but before that, there are many problems to be solved.