Self‐Powered UVC and X‐Ray Photodetection in Single Sn‐Doped β‐Ga ₂ O ₃ Microwire Schottky Diodes

Abstract Gallium oxide (Ga 2 O 3 ) microwires, characterized by a high surface‐to‐volume ratio and wide bandgap, enhance the responsivity (R λ ) of UVC photodetectors beyond conventional planar Ga 2 O 3 designs. This study reports the microfabrication and characterization of Schottky photodiodes (SPDs) based on single Sn‐doped β–Ga 2 O 3 microwires. Platinum (Pt) and single‐layer graphene (SLG) serve as Schottky contacts, combined with complementary metal–oxide–semiconductor‐compatible ohmic contacts (Ti/Al 98.5 Si 1.0 Cu 0.5 /TiW). Nano X‐ray fluorescence and electrical analysis reveals a Sn doping range of (4 × 10 18 –1.24 × 10 19 cm −3 ) and a significant density of surface states. Under UVC illumination, these surface states dynamically modulate the Schottky barrier height through the trapping and detrapping of photogenerated holes at the Schottky junction, leading to high internal gain and fast decay without persistent photoconductivity. The Pt/SLG‐based SPDs achieves R λ up to ≈713 A W −1 at −3 V and self‐powered operation with R λ ≈1.92 A W −1 at 0 V. Additionally, the device exhibits self‐powered photoresponse under 30.5 keV X‐ray irradiation. While Pt‐based SPDs show long rise times due to delayed hole transit, SLG‐based SPDs demonstrate faster response (<150 ms) enabled by SLG's high UVC transparency. These results highlight the potential of microwire‐based Ga 2 O 3 SPDs for fast, high‐gain, self‐powered photodetection.