1. Third-generation semiconductors: “wide bandgap pioneers” for mature applications
The third generation of semiconductors is also called "wide bandgap semiconductors". The core feature is that the bandgap width (the energy required for electrons in semiconductors to jump from the valence band to the conduction band) is significantly larger than that of traditional silicon-based semiconductors (the bandgap width of silicon is about 1.12eV). The main materials areSilicon carbide (SiC)andGallium nitride (GaN), and has been gradually industrialized since the 1980s.
High temperature / high pressure resistance: The bandgap width is 2.8-3.4eV, it can withstand operating temperatures exceeding 600°C, and the breakdown electric field strength is 5-10 times that of silicon (SiC is about 2.5MV/cm, GaN is about 3.3MV/cm), making it suitable for high-voltage power electronics scenarios.
High frequency / low loss: The electron mobility is 2-3 times that of silicon, the switching loss is low, and it is suitable for high-frequency signal processing.
High power density：It can carry higher power in the same volume and reduce the size of the device (for example, the volume of the power module can be reduced by more than 50%).
Power electronics: power devices for new energy vehicles (SiC inverters can reduce energy consumption by 10%), high-voltage power transmission and transformation equipment, and photovoltaic inverters.
RF communications: 5G base station RF amplifiers (GaN devices are 30% more efficient than traditional LDMOS), satellite communication transceivers.
Consumer electronics: Fast charging chargers (GaN fast charging is 40% smaller than silicon-based ones).
The technology is highly mature and has been commercialized on a large scale; the industry chain is well-developed (with leading companies covering everything from material substrates to device packaging, such as Cree in the United States and San'an Optoelectronics in China); and although the cost is higher than silicon, it is gradually decreasing as production capacity expands (the price of SiC substrates has fallen by 60% compared to 2015).
The fourth generation of semiconductors are "ultra-wide bandgap semiconductors" with a bandgap width generally exceeding 4eV. They are an upgrade of the third generation to meet "higher extreme environmental requirements". The core materials includeGallium oxide (Ga₂O₃) 、Diamond (C) 、Aluminum nitride (AlN), and is currently still in the transition stage from laboratory research and development to pilot production.
Larger bandgap: Ga₂O₃ is about 4.8eV, diamond is about 5.5eV, the breakdown electric field strength is 2-4 times that of SiC (Ga₂O₃ is about 8MV/cm, diamond is about 12MV/cm), and can withstand higher voltages (a single device supports more than 10kV, far exceeding the 3kV upper limit of SiC).
Stronger high temperature resistance: The operating temperature of diamond can exceed 800℃, which is suitable for extreme high temperature scenarios such as aerospace, nuclear industry, etc.
Better thermal conductivity: The thermal conductivity of diamond is five times that of SiC (approximately 2000W/(m・K)), solving the heat dissipation bottleneck of high-power devices.
Potentially lower costs: Ga₂O₃ substrate can be prepared by melt method, and the cost is only 1/10 of SiC (theoretically).
Extreme power electronics: ultra-high voltage transmission and transformation (smart grid above 10kV), high-power ship propulsion systems, and power supplies for nuclear fusion devices.
Extreme environment devices: aircraft engine sensors, nuclear reactor monitoring chips, and deep space exploration equipment.
Emerging fields: deep ultraviolet optoelectronic devices (AlN-based deep ultraviolet LEDs, with a sterilization efficiency 50% higher than traditional ultraviolet lamps), and quantum computing chip substrates.
The technology is not mature enough and key bottlenecks have not been broken through:
Many material defects: The defect density of Ga₂O₃ single crystal substrate is 100-1000 times that of SiC, which affects device reliability;
Difficulty in doping: Diamond’s p-type doping efficiency is low, making it difficult to fabricate high-performance transistors;
Imperfect industrial chain: lack of supporting technologies such as large-scale substrate production and device packaging;
The application scenarios have not yet been fully opened up and are mainly driven by military industry and high-end scientific research needs.
The third generation is the "current workhorse"：With mature technology and commercial capabilities, it is rapidly replacing silicon-based products in the field of civilian high-end electronics and is the "lander" of wide bandgap semiconductors;
The fourth generation is the "future direction": It breaks through the limits of the third generation with its ultra-wide bandgap performance advantage, targeting extreme environments and higher power requirements. However, it needs to solve problems such as material defects and industrial chain support, and is unlikely to be commercialized on a large scale in the short term.
The two are not "substitutes": The third generation focuses on medium and high voltage (1-3kV) and medium and high frequency scenarios, and the fourth generation focuses on ultra-high voltage (above 10kV) and extreme environments. In the future, a stepped application pattern of "silicon-based - third generation - fourth generation" will be formed.
