Silicon (Si) material is the mainstream semiconductor material for a long time because of its relatively excellent hightemperature resistance, radiation resistance, low price, and huge reserves. However, with the rapid development of power electronics technology, the development of technology has reached a bottleneck period, and Moore's law has gradually failed. The existing silicon-based semiconductor devices are close to the theoretical limit of Si materials and can no longer meet the performance requirements of future power devices. However, the cost of transistors is constantly rising, and the performance improvement is slow, gradually moving towards the post-Moore era. To further improve the performance of the device, it is necessary to seek new technologies or new materials to support the continuous development of power devices, and the core of the progress of power semiconductor devices is the development of semiconductor materials. As the third generation of wide band gap semiconductors, gallium nitride (GaN) has been superior to Si in terms of material properties. GaN has the advantages of a wide band gap, high critical field strength, high electron saturation velocity, high conductivity, high-temperature resistance, and high voltage resistance. Compared with traditional Si-based power devices, it not only has higher breakdown voltage, low on-resistance, high electron mobility and good thermal conductivity, but also has smaller device volume and better heat dissipation performance under the same performance, which greatly reduces power consumption and achieves the effect of energy saving and emission reduction. The cost of early GaN single crystal preparation and epitaxial growth is beyond reach. However, with the mature development of growth technology, not only the cost of GaN single crystal substrate and its epitaxial growth is decreasing, but also the quality is gradually increasing, which lays a solid foundation for the wide application of GaN power devices in the future. This paper lists the main physical parameters of GaN and other semiconductor materials, the preparation of GaN single crystal, and the main methods of its epitaxy growth, and describes the advantages of GaN power devices in the current environment. For the device structure, the problems of the lateral device and the advantages of the vertical device are listed, and why the vertical device can become the mainstream structure of future power devices is explained. On this basis, the structure, working principle, research progress, and existing problems of vertical current aperture GaN transistor (CAVET), trench GaN MOSFET, vertical trench MOSFET based on in-situ oxidation GaN interlayer (GaN OG-FET), and vertical GaN fin field effect transistor (GaN FinFET) are introduced in detail. The performance parameters of vertical GaN power transistors mentioned in this paper are summarized in tables according to device types and time sequence, and the general direction of the development of GaN power transistors in the future is proposed. For integrated circuit systems, the special requirements and key technologies of GaN power devices in driver chips are summarized. Finally, for the current market environment, listing the vertical GaN power transistor in the medium and low voltage range is a more popular and promising application scenario.
