关键词: β-Ga₂O₃; 晶体生长; 超精密加工; 化学机械抛光; 半导体材料

Abstract: β-Ga₂O₃， an ultra-wide-bandgap semiconductor with a bandgap of 4.8~4.9 eV， has attracted significant attention owing to its exceptionally high Baliga’s figure of merit， outstanding deep-ultraviolet （DUV） photoresponse， and strong radiation hardness. These attributes make it one of the most promising candidate materials for next-generation power electronics， optoelectronic devices， and nuclear-radiation detectors. Over the past decade， rapid progress has been achieved in the growth of large-size single crystals and the development of ultra-precision machining techniques that enable the production of device-quality substrates. This review aims to provide a comprehensive overview of the state-of-the-art in β-Ga₂O₃ crystal growth and surface processing， highlight recent breakthroughs， and identify key challenges for future research and industrial application. In terms of single-crystal growth， several melt-based methods—including edge-defined film-fed growth （EFG）， vertical Bridgman （VB）， Czochralski （Cz）， floating-zone （FZ）， and the more recently developed cold crucible （OCCC） approaches—have been systematically optimized. Industrial-scale production of 6-inch wafers has been achieved via EFG and VB techniques， while domestic innovations using casting methods have successfully produced 8-inch wafers， representing a global technological milestone. Doping strategies， such as Sn， Si， and Mg incorporation， allow carrier concentrations to be tailored over a wide range （10¹⁵~10¹⁹ cm^-3）， thereby enabling conductivity control from the insulating to the highly conducting regimes and enhancing the versatility of the material for device applications. Beyond traditional size scaling， research efforts are increasingly directed toward understanding defect formation， reducing dislocation densities， and ensuring wafer uniformity. From a machining perspective， β-Ga₂O₃ presents formidable challenges due to its strong anisotropy， chemical inertness， and brittle nature. Multi-stage grinding combined with chemical-mechanical polishing （CMP） has achieved a surface roughness below 0.2 nm， suitable for device integration. Atmospheric-pressure plasma etching further reduces roughness to atomic levels （Ra≈0.05 nm）， while simultaneously mitigating subsurface defects and improving luminescence performance. In addition， ultrafast laser micromachining， particularly when assisted by liquids or coupled with water-jet techniques， has emerged as a promising method for fabricating damage-free microstructures and functional surfaces. These approaches are complemented by emerging plasma-enabled atomic-scale processes that provide near-damage-free planarization and surface reconstruction， opening up new opportunities for atomic- and close-to-atomic-scale manufacturing. Despite these advances， several critical challenges remain. The growth of large-diameter crystals continues to face issues of limited yield， defect accumulation， and high production costs due to crucible degradation and thermal instability. On the machining side， the lack of quantitative models to describe the initiation and evolution of subsurface damage limits the predictive design of processes. Furthermore， a deeper mechanistic understanding is required regarding the coupling between surface morphology， microstructural defects， and device performance. Addressing these gaps will necessitate cross-disciplinary strategies， including multi-scale simulation of thermal-mechanical fields， in-situ monitoring of stress and defect evolution， and the integration of artificial intelligence for process optimization. In conclusion， the research progress on β-Ga₂O₃ single-crystal growth and ultra-precision machining has brought the material to the verge of industrial deployment. The combination of large-size， high-quality wafers with atomic-level surface finishing provides a robust foundation for its application in high-power electronics and DUV photodetectors. Future advances are expected to focus on improving growth yields， reducing costs， and innovating multi-field synergistic processing methods. Collectively， these efforts will accelerate the transition of β-Ga₂O₃ from a laboratory material to a cornerstone of next-generation semiconductor technology.

Key words: β-Ga₂O₃; crystal growth; ultra-precision machining; chemical mechanical polishing; semiconductor material