【Device Papers】Self-Powered UVC and X-Ray Photodetection in Single Sn-Doped β-Ga₂O₃ Microwire Schottky Diodes

      Researchers from the INESC Microsystems and Nanotechnologies (INESC MN) have published a dissertation titled "Self-Powered UVC and X-Ray Photodetection in Single Sn-Doped β-Ga₂O₃ Microwire Schottky Diodes" in Advanced Materials Technologies.

Abstract

      Gallium oxide (Ga₂O₃) microwires, characterized by a high surface-to-volume ratio and wide bandgap, enhance the responsivity (R_λ) of UVC photodetectors beyond conventional planar Ga₂O₃ designs. This study reports the microfabrication and characterization of Schottky photodiodes (SPDs) based on single Sn-doped β–Ga₂O₃ microwires. Platinum (Pt) and single-layer graphene (SLG) serve as Schottky contacts, combined with complementary metal–oxide–semiconductor-compatible ohmic contacts (Ti/Al_98.5Si_1.0Cu_0.5/TiW). Nano X-ray fluorescence and electrical analysis reveals a Sn doping range of (4 × 10¹⁸–1.24 × 10¹⁹ 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 Ga₂O₃ SPDs for fast, high-gain, self-powered photodetection.

DOI：

https://doi.org/10.1002/admt.202501212