Review of Amorphous Gallium Oxide: From Material Synthesis to Device Applications

Amorphous gallium oxide (a‐Ga 2 O 3 ) has emerged as a promising material for ultraviolet (UV) optoelectronic applications, particularly solar‐blind photodetection, due to its wide bandgap, high transparency, and compatibility with low‐temperature, large‐area deposition. This review summarises key aspects of a‐Ga 2 O 3 , including material properties, deposition techniques, device architectures, and performance limitations. Special emphasis is placed on the role of structural disorder, localised states, Urbach tails, and trap‐assisted transport in governing electronic and optical behaviour. Photodetector performance metrics such as responsivity, detectivity, and temporal response are critically examined, with attention to inconsistencies in reported data. A comparison of device structures (e.g., MSM, Schottky, and heterojunction) reveals a trade‐off between high responsivity and response speed, largely driven by defect‐mediated carrier trapping and persistent photoconductivity. Current challenges, including high defect densities, low carrier mobility, and slow response, are discussed alongside emerging strategies for improvement. The potential of a‐Ga 2 O 3 for flexible and unconventional substrates is also highlighted. Overall, this work outlines key directions for advancing a‐Ga 2 O 3 towards reliable and practical UV sensing applications.