Fabrication of Highly Anisotropic Large‐Area β‐Ga₂O₃ Thin Films via Crystal Orientation Engineering for Multifunctional Solar‐Blind Polarization‐Sensitive Photodetectors

Solar‐blind polarization‐sensitive photodetector exhibits high selectivity for deep UV light, making it valuable for applications in secure communication, fast radio burst monitoring, industrial material inspection, and so on. β ‐Ga 2 O 3 is particularly well‐suited for photodetector applications due to its optimal optical bandgap and low‐symmetry crystal structure, which provides strong photoelectric anisotropy. However, most heteroepitaxial β ‐Ga 2 O 3 thin films exhibit isotropic properties due to symmetry inheritance from substrates during heteroepitaxy, fundamentally limiting polarization‐sensitive photodetector development. By exploiting the crystallographic‐orientation‐dependent growth via plasma‐enhanced chemical vapor deposition on r ‐plane sapphire substrates, a significant dichroic absorption ratio is achieved in (201)‐oriented β ‐Ga 2 O 3 films in this work. This intrinsic anisotropy enables polarization discrimination without external optics, yielding a polarization ratio of 6.02 under 254 nm illumination. More importantly, by leveraging the unique properties of the fabricated photodetector, several innovative applications, including polarized solar‐blind UV imaging, secure UV communication, and logic circuits are successfully developed. This substrate‐orientation engineering strategy resolves the longstanding symmetry‐mismatch limitation in heteroepitaxial films, advancing polarization‐sensitive photodetectors.