Development of third-generation semiconductor materials in various countries around the world

Due to the significant performance advantages and huge industrial driving effect of third-generation semiconductor materials, developed countries and regions such as Europe, America, and Japan have included the development of silicon carbide semiconductor technology in their national strategies and invested heavily in supporting its development. This article will provide a detailed analysis of the definition, characteristics, and research and development status of third-generation semiconductor materials in various countries.

• Overview of First Generation Semiconductor Materials

The first generation of semiconductor materials mainly refers to silicon (Si) and germanium (Ge) semiconductor materials. As the first generation of semiconductor materials, germanium and silicon have been widely used in various discrete devices and applications in the international information industry, including integrated circuits, electronic information network engineering, computers, mobile phones, televisions, aerospace, various military engineering, and rapidly developing new energy and silicon photovoltaic industries. Silicon chips shine with their brilliance in every corner of human society.

• Overview of second-generation semiconductor materials

The second generation of semiconductor materials mainly refers to compound semiconductor materials, such as gallium arsenide (GaAs) and indium antimonide (InSb); Ternary compound semiconductors, such as GaAsAl and GaAsP; There are also some solid solution semiconductors, such as Ge Si, GaAs GaP; Glass semiconductors (also known as amorphous semiconductors), such as amorphous silicon and glassy oxide semiconductors; Organic semiconductors such as phthalocyanine, copper phthalocyanine, polyacrylonitrile, etc.

The second-generation semiconductor materials are mainly used to produce high-speed, high-frequency, high-power, and luminescent electronic devices, and are excellent materials for producing high-performance microwave, millimeter wave devices, and luminescent devices. Due to the rise of information highway and Internet, it is also widely used in satellite communication, mobile communication, optical communication, GPS navigation and other fields.

• Third generation semiconductor materials

1、Definition

The third-generation semiconductor materials mainly include wide bandgap (Eg>2.3eV) semiconductor materials represented by silicon carbide (SiC), gallium nitride (GaN), zinc oxide (ZnO), diamond, and aluminum nitride (AlN).

2、Application area 

The third-generation semiconductor materials, represented by SiC, will be widely used in fields such as optoelectronic devices and power electronic devices. With their excellent semiconductor performance, they will play an important innovative role in various modern industrial fields, with huge application prospects and market potential.

With the reduction of SiC production costs, SiC semiconductors are gradually replacing Si semiconductors with their excellent properties, breaking the bottleneck encountered by Si based materials due to their inherent properties. Undoubtedly, it will trigger an industrial revolution similar to the steam engine:

1. The application of SiC materials in the high-speed rail field can save energy by more than 20% and reduce the size of the power system;

2. The application of SiC materials in the field of new energy vehicles can reduce energy consumption by 20%;

3. SiC materials applied in the field of household appliances can save 50% energy;

4. The application of SiC materials in the field of wind power generation can improve efficiency by 20%;

5. The application of SiC materials in the field of solar energy can reduce photoelectric conversion losses by more than 25%;

6. SiC materials applied in the field of industrial motors can save energy by 30% -50%;

The application of SiC materials in ultra-high voltage direct current transmission and smart grid fields can reduce power loss by 60% and improve power supply efficiency by more than 40%;

The application of SiC materials in the field of big data can significantly reduce energy consumption in data centers;

The application of SiC materials in the field of communication can significantly improve the efficiency, safety, and stability of signal transmission;

SiC material can reduce equipment losses by 30% -50% in the aerospace field, increase operating frequency by three times, shrink the volume of inductors and capacitors by three times, and significantly reduce the weight of heat sinks.

3、Material characteristics

Compared with the first and second generation semiconductor materials, the third generation semiconductor materials have a wider bandgap, higher breakdown electric field, higher thermal conductivity, higher electron saturation rate, and higher radiation resistance, making them more suitable for producing high-temperature, high-frequency, radiation resistant, and high-power devices. They are commonly referred to as wide bandgap semiconductor materials (with a bandgap greater than 2.2 electron volts) or high-temperature semiconductor materials. From the current research on third-generation semiconductor materials and devices, SiC and GaN semiconductor materials are relatively mature, while research on materials such as zinc oxide, diamond, and aluminum nitride is still in its infancy.

Compared to Si, SiC has many advantages: it has 10 times the electric field strength, 3 times higher thermal conductivity, 3 times wider bandgap, and 1 time higher saturation drift velocity. Due to these characteristics, devices made of SiC can be used under extreme environmental conditions. Microwave and high-frequency and short wavelength devices are currently mature application markets. SiC MESFET with a frequency of 42GHz is used in military phased array radar and communication broadcasting systems. High brightness blue LED with SiC as the substrate is a key component of full-color large-area display screens.

Doping nitrogen or phosphorus into silicon carbide (SiC) can form n-type semiconductors, while doping aluminum, boron, gallium, or beryllium can form p-type semiconductors. Doping a large amount of boron, aluminum, or nitrogen into silicon carbide can endow the doped silicon carbide with conductivity on the order of magnitude comparable to that of metals. 3C SiC doped with Al, 3C SiC doped with B, and 6H SiC silicon carbide can all exhibit superconductivity at a temperature of 1.5K, but the magnetic field behavior of Al doped and B doped silicon carbide is significantly different. Both aluminum doped silicon carbide and B-doped crystalline silicon are type II semiconductors, but boron doped silicon carbide is type I semiconductor.

Gallium nitride (GaN) is a compound of nitrogen and gallium, which has a structure similar to wurtzite and high hardness. As an emerging semiconductor process technology, it provides multiple advantages beyond silicon. Compared with silicon devices, GaN has achieved a performance leap in power conversion efficiency and power density.

GaN has excellent breakdown capability, higher electron density and speed, and higher operating temperature. Gallium nitride has a wide bandgap of 3.4 electron volts and is widely used in power factor correction (PFC), soft switching DC-DC and other power system designs, as well as in terminal fields such as power adapters, photovoltaic inverters or solar inverters, servers and communication power supplies.

GaN is an extremely stable compound and a hard high melting point material, with a melting point of about 1700 ° C. GaN has a high ionization degree and can be used in III. - V. Among the compounds in the group, it is the highest (0.5 or 0.43). Under atmospheric pressure, GaN crystals generally have a hexagonal wurtzite structure. It has 4 atoms in one cell, with an atomic volume approximately half that of GaAs. Because of its high hardness and excellent coating protection material.

The electrical properties of GaN are the main factors affecting devices. GaN without intentional doping is n-type in various situations, and the best sample has an electron concentration of about 4 × 1016/cm3. In general, the P-type samples prepared are highly compensated.

4、Representative countries

In early 2014, US President Obama announced the establishment of the "National Manufacturing Innovation Center for Next Generation Power Electronics Technology", hoping to strengthen the research and industrialization of third-generation semiconductor technology, enabling the United States to occupy the largest and fastest-growing emerging market in the next generation power electronics industry, and create a large number of high-income jobs for the United States.

Japan has also established the "Next Generation Power Semiconductor Packaging Technology Development Alliance", led by Osaka University, in collaboration with 18 well-known enterprises, universities, and research centers engaged in the development and industrialization of SiC and GaN materials, devices, and application technologies, such as ROHM, Mitsubishi Electric, and Panasonic, to jointly develop advanced packaging technologies that adapt to the characteristics of next-generation power semiconductors such as SiC and GaN.

Europe has launched the industry university research project "LASTPOWER", led by STMicroelectronics, in collaboration with private enterprises, universities, and public research centers from six European countries including Italy and Germany, to jointly tackle key technologies for SiC and GaN. The project aims to elevate Europe to the forefront of research and commercialization of energy-efficient power chips by developing cost-effective and highly reliable SiC and GaN power electronics technologies.

In May 2015, China established a joint innovation base for third-generation semiconductor materials and applications, seizing a new strategic high ground for third-generation semiconductors. It also signed a strategic cooperation agreement with Delft University of Technology in the Netherlands, marking new progress in introducing international advantageous innovation resources and gathering global innovative and entrepreneurial talents.

In the future, power devices made of semiconductor SiC materials will support the development trend of today's energy-saving technology and become the core components of energy-saving equipment. Therefore, semiconductor SiC power devices are also known as the "CPU" of power converters and the "core" of green economy in the industry.

5、Research and development of third-generation semiconductor materials in China

It is reported that the Chinese government attaches great importance to the research and development of third-generation semiconductor materials. Since 2004, it has deployed research in the field of third-generation semiconductors and launched a series of major research projects. In 2013, the Ministry of Science and Technology explicitly listed third-generation semiconductor materials and applications as important content in the 863 Program New Materials Technology Project Collection Guidelines.

The industry is generally optimistic about the market development prospects of SiC. According to predictions, its market size will reach 4 billion US dollars by 2022, with an average annual compound growth rate of 45%, which will stimulate huge market application space.

Although the prospects are promising, the biggest bottleneck for China's development in this field is raw materials. The quality and preparation issues of SiC raw materials in our country urgently need to be resolved. At present, there is still a gap in the preparation of SiC crystal cells in China, and most of the equipment is imported from abroad.

The research work on SiC and GaN materials and devices in China started relatively late, and the level is lower compared to foreign countries. The obstacle to the progress of third-generation semiconductor research in China is also the problem of original innovation. Most domestic research institutes and related production enterprises in the field of new materials are eager for quick success and cannot tolerate the long-term situation of "only investing, not producing". Therefore, the original innovation of new materials represented by third-generation semiconductor materials is struggling.

The output downstream of the industrial chain should be based on upstream materials, but in fact, China's attention to basic material issues is not enough. Once the investment and support are not sufficient, it will be difficult to attract relevant talents, and the problem of talent team construction will gradually become a bottleneck for development.

However, at the first International Symposium on the Development of Third Generation Semiconductor Materials and Applications, Vice Minister of Science and Technology Cao Jianlin stated that "China today has already reached the forefront of technology in the world, let alone being the largest economic system in the world. We should work together with our peers around the world to solve the problems we face. Moreover, with the strengthening of the Chinese government's support and encouragement of innovation, we believe that China has the ability to solve these problems. This is not only a huge push for China, but also for scientific and technological work around the world“

In addition, the attending experts also believe that unlike the situation where China has been lagging behind for many years in the first and second generation semiconductor materials and integrated circuit industries, and it is difficult to catch up with the international advanced level, China's research work in the third generation semiconductor field has always kept up with the world's forefront, and the engineering technology level is not far behind the international advanced level. It has developed from tracking and imitating to keeping pace, and may even gain leading and comparative advantages in some fields, and has the opportunity to surpass them.

Therefore, with the increasing support at the national strategic level, especially with China having a relatively good industrial foundation in energy conservation and emission reduction, as well as rapid development of information technology, and an urgent market demand, China is expected to concentrate its advantageous forces to achieve overtaking and take the lead in the market.