Crystal Phase‐Driven Oxygen‐Vacancy‐Mediated High‐Performance Ga ₂ O ₃ Solar‐Blind Ultraviolet Detectors

Lattice and microstructural phases are always critical for controlling optical, electronic, and optoelectronic characterizations of semiconductor materials and their functional devices. Gallium oxide (Ga 2 O 3 ) is widely recognized as a promising material for solar‐blind ultraviolet photodetectors, with both amorphous and crystalline phases offering distinct advantages. Nevertheless, inherent crystallinity issues still hinder device performance and practical application. In this work, we systematically investigated the correlation between microstructure and dynamic evolution of photogenerated carriers in Ga 2 O 3 via crystal phase manipulation. High‐performance nanocrystalline Ga 2 O 3 photodetectors were demonstrated with a high detectivity of 3.50 × 10 13 Jones and a larger photo‐to‐dark current ratio up to 5.56 × 10 4 . Related photoresponsivity and rejection ratio of the ultraviolet photodetectors were significantly modulated by amorphous, nanocrystalline, and multicrystalline microstructural phases. This modulation is attributed to oxygen‐vacancy‐related defects, which introduce additional energy levels acting as electron donors that significantly alter the carrier concentration and thus regulate the signal intensity of the photoresponse. These insights underscore the critical role of structural phase engineering in Ga 2 O 3 and provide valuable guidance for the design and optimization of high‐performance solar‐blind ultraviolet photodetectors.