Fabrication of Solid‐Solution Thin Films via Liquid‐Metal van der Waals Exfoliation for High Signal‐to‐Noise Ratio Visible‐Light Imaging

The GaZnON solid solution has been recognized as a promising visible‐light‐driven photosensitive medium. However, its practical applications in photodetection/imaging are severely hindered by the lack of scalable thin‐film fabrication methods due to its isotropic 3D growth behavior. Herein, large‐scale GaZnON thin films were initially synthesized via liquid‐metal van der Waals exfoliation and urea‐assisted ammonolysis, and their application potential was validated in photodetectors and single‐pixel imaging. The two‐step fabrication strategy utilized the thin oxide layer naturally grown on a Ga–Zn liquid alloy (melting point ∼30 °C, Zn/Ga ≈ 3.87 at%), yielding GaZnON films as thin as around 50 nm. Characterization analyses confirm the polycrystalline nature of the GaZnON film and its visible light absorption property is found to be associated with Zn‐related acceptor levels. GaZnON‐based photodetectors exhibited a responsivity of 266 mA W ⁻¹ , an external quantum efficiency of 81%, and a detectivity of 1.4 × 10 ¹¹ Jones when illuminated with 405 nm light (0.683 mW/cm ² , 5 V). For single‐pixel imaging with a 405 nm laser, the device achieved a signal‐to‐noise ratio of 60 ± 5 dB under a 5 V bias, outperforming previously reported semiconductor imagers, even commercial silicon‐based alternatives. This work provides an effective route for the large‐scale production of thin solid solution semiconductors for advanced optoelectronic systems.