Gallium oxide (Ga ₂ O ₃ ), an emerging ultra-wide-bandgap semiconductor, has the desirable properties of a large bandgap of 4.6–4.9 eV, an estimated critical breakdown field of 8 MV cm ⁻¹ , decent electron mobility of 250 cm ² V s ⁻¹ and high theoretical Baliga figures of merit (BFOMs) of around 3000. Bolstered by their capability of an economical growth technique for high-quality bulk substrate, β -Ga ₂ O ₃ -based materials and devices have been highly sought after in recent years for power electronics and solar-blind ultraviolet photodetectors. This article reviews the most recent advances in β -Ga ₂ O ₃ power device technologies. It will begins with a summary of the field and underlying semiconductor properties of Ga ₂ O ₃ , followed by a review of the growth methods of high-quality β -Ga ₂ O ₃ bulk substrates and epitaxial thin films. Then, brief perspectives on the advanced technologies and measurements in terms of ohmic contact and interface state are provided. Furthermore, some state-of-the-art β -Ga ₂ O ₃ photoelectronic devices, power devices and radiofrequency devices with distinguished performance are fully described and discussed. Some solutions to alleviating challenging issues, including the difficulty in p-type doping, low thermal conductivity and low mobility, are also presented and explored.

In this letter, we report on demonstrating high-performance field-plated lateral β-Ga ₂ O ₃ Schottky barrier diode (SBD) on a sapphire substrate with a reverse blocking voltage of more than 3 kV and a low dc specific ON-resistance (R _ON,sp ) of 24.3 mΩ·cm ² at an anode-cathode spacing (L _AC ) of 24 μm. To the best of our knowledge, this lateral breakdown voltage (BV) >3 kV with dc power figure-of-merit (FOM) >370 MW/cm ² is the highest BV achieved among all the β-Ga ₂ O ₃ SBDs. Meanwhile, lateral β-Ga ₂ O ₃ SBD with L _AC = 16 μm also demonstrates a high BV of 2.25 kV and low R _ON,sp = 10.2 mΩ·cm ² , yielding a record high dc power FOM of 500 MW/cm ² . Combining with 109 high-current ON/OFF ratio, 1.15-eV Schottky barrier height and 1.25 ideality factor, β-Ga ₂ O ₃ SBD with field-plate structure shows its great promise for power electronics applications.