Gallium oxide (Ga₂O₃) has been hailed as the "bright new star" of the next generation of semiconductor materials in recent years, and has attracted much attention due to its unique physical properties and wide application potential.

As a representative of the fourth generation of ultra-wide bandgap semiconductor materials, gallium oxide (Ga₂O₃) is gradually emerging with its excellent performance. The bandgap width of gallium oxide is as high as 4.8-4.9 eV, far exceeding the 3.25 eV of silicon carbide and the 3.4 eV of gallium nitride. Its theoretical breakdown field strength can reach 8 MV/cm, which is 2.5 times that of gallium nitride and more than 3 times that of silicon carbide. Gallium oxide is also amazing in terms of energy efficiency. According to statistics, its theoretical loss is only 1/3000 of silicon, 1/6 of silicon carbide, and 1/3 of gallium nitride. In addition, gallium oxide also has excellent chemical and thermal stability, and the preparation process is simple and efficient, which lays a solid foundation for large-scale industrial applications. With these excellent properties, gallium oxide has shown broad application prospects in power electronics fields such as power grids, new energy vehicles, rail transportation, and 5G communications. According to market forecasts, by 2030, the market size of gallium oxide power components is expected to exceed hundreds of billions of yuan.

Core characteristics of Gallium oxide (Ga₂O₃)

Ultra-wide Bandgap (UWBG)

The bandgap of gallium oxide is as high as 4.5-4.9 eV, which is much higher than the common wide bandgap materials currently available, such as:

Silicon carbide (SiC): about 3.3 eV

Gallium nitride (GaN): about 3.4 eV

It can withstand higher electric field strengths, giving it excellent application potential in high voltage and high power scenarios.

High breakdown electric field strength

The breakdown electric field strength of gallium oxide exceeds 8 MV/cm, which is about twice that of SiC and three times that of GaN. This allows gallium oxide-based devices to be designed to be smaller and more efficient.

High thermal conductivity and stability

Although the thermal conductivity of gallium oxide is slightly lower than that of SiC and GaN, it has excellent thermal stability and is suitable for use in high temperature environments.

Available large-size single crystal growth

Gallium oxide can be produced in large-size single crystals by molten salt methods (such as Edge-defined Film-fed Growth, EFG), which is low-cost and suitable for large-scale production.

Preparation method of Gallium oxide (Ga₂O₃)

Gallium oxide (Ga2O3) has five different crystal phases, namely α, β, γ, δ and ε, which can be transformed into each other under specific conditions. Among these five crystal phases, β-Ga2O3 is the most stable at room temperature and pressure and is the main form of existence, while the other crystal phases are considered metastable phases. By adjusting the temperature conditions, these metastable phases can be transformed into β-Ga2O3, and this process is reversible under certain conditions, but usually requires high pressure to achieve. For example, under extreme conditions of 4.4 GPa and 1000℃, β-Ga2O3 will transform into the metastable phase of α-Ga2O3. β-Ga2O3 belongs to the monoclinic system, with a C2/m space group, and its lattice constants are a=(1.2323±0.002)nm, b=(0.304±0.001)nm and c=(0.580±0.001)nm. In its unit cell structure, oxygen atoms occupy three different positions (O1, O, Om), while gallium atoms occupy two positions (GaⅠ and GaⅡ), forming a distorted tetrahedral structure (GaⅠ) and a highly distorted octahedral structure (GaⅡ). This structural feature, especially the corner-sharing of the tetrahedral structure and the edge-sharing of the octahedral structure, facilitates the movement of free electrons and is the structural basis for the conductive properties of gallium oxide.

At present, there are many methods for preparing gallium oxide, including the Czochralski method, the guided-mode method, the flame method, the optical floating zone method, and thin film preparation technology. Among them, thin film preparation technologies such as molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD) and pulsed laser deposition (PLD) have become research hotspots due to their flexible, simple and highly repeatable processes.

Application fields of Gallium oxide (Ga₂O₃)

High-power electronic devices

Used for high-voltage switches (such as inverters and rectifiers for power electronics).

Replace traditional silicon devices in electric vehicle chargers and high-voltage transmission systems to improve efficiency.

RF and microwave devices

Suitable for high-frequency applications such as 5G base stations and radars.

Compared to GaN, gallium oxide can support higher power density.

Ultraviolet detectors

Gallium oxide is highly sensitive to deep ultraviolet light (200-280 nm) and can be used in deep ultraviolet light detectors.

Applied to germicidal lamp monitoring, ultraviolet detection in the aerospace field, etc.

Solar blind ultraviolet photoelectric detection

Its wide bandgap characteristics make gallium oxide appear "solar blind" in solar radiation, focusing on detection in the ultraviolet band.

Comparison of the advantages of Gallium oxide (Ga₂O₃)

Future development direction

Material optimization

Improve thermal conductivity and mechanical strength.

Research new doping technologies to achieve p-type characteristics.

Manufacturing process improvement

Optimize wafer production processes and reduce manufacturing costs.

Develop more efficient packaging technologies suitable for gallium oxide.

Industrialization promotion

Promote the commercialization of gallium oxide devices in electric vehicles, high-voltage power grids and defense.

Expand complementary applications with GaN and SiC materials.

Globally, Japan maintains a leading position in gallium oxide research and has successfully achieved industrial production of 4-inch and 6-inch gallium oxide wafers. At the same time, the United States, mainland China and Taiwan are also actively following up and continuously promoting gallium oxide related research and product development.

Challenges

Insufficient thermal conductivity

Although gallium oxide has a bandgap width and a strong breakdown electric field, its thermal conductivity is lower than that of SiC and GaN, which may lead to difficulties in heat dissipation in high-power scenarios.

Difficulty in p-type doping

Gallium oxide naturally tends to have n-type characteristics. At present, there are still technical difficulties in achieving stable p-type doping, which limits its application in some fields.

Process maturity

Gallium oxide-related device manufacturing and packaging technologies are not yet fully mature, and commercial applications are still in the early stages.

Summary

Gallium oxide is becoming an important candidate material in the field of high-power semiconductors due to its excellent physical properties. Although there are still some technical challenges to overcome, with technological breakthroughs and commercialization, gallium oxide is expected to occupy an important position in the fields of high-voltage power electronics, radio frequency communications and ultraviolet detection.