【Device Papers】Ultrawide bandgap NiCo/β-Ga₂O₃ Schottky detectors for solar-blind UV response, low-dose X-ray detection, and X-ray imaging

      Researchers from Sejong University have published a dissertation titled " Ultrawide bandgap NiCo/β-Ga₂O₃ Schottky detectors for solar-blind UV response, low-dose X-ray detection, and X-ray imaging " in Surfaces and Interfaces.

Abstract

      Next-generation X-ray detectors require ultrawide bandgap (UWBG) semiconductors with high resistivity, radiation hardness, and low defect densities. β-Ga₂O₃, with its excellent material properties and scalable substrates, is a promising candidate for advanced radiation detection. In this work, NiCo/β-Ga₂O₃ Schottky barrier diodes (SBDs) were fabricated and systematically investigated. The devices exhibited a low specific on-resistance (R_on,sp) of 0.14 Ω-cm² and a high breakdown voltage (BV) (V_BR) of ∼730 V. Deep-level transient spectroscopy (DLTS) identified three electron traps associated with intrinsic defects and impurity-related states, which influence leakage current and breakdown behavior through trap-assisted conduction. Under solar-blind UV-C illumination (240 nm), the NiCo/β-Ga₂O₃ SBDs demonstrated a high responsivity (R) of 0.76 A/W, external quantum efficiency (EQE) exceeding unity, and high detectivity (D*), enabled by efficient carrier separation and photoconductive gain. The devices showed stable transient response with rise and decay times of ∼1 s. Under X-ray irradiation, a low dark current (I_dark) of 2.57 × 10^–8 A/cm², linear dose-rate response (0.1–3.8 mGy·s⁻¹), sensitivity of 0.8 μC/mGy·cm², and SNR of 78.6 were achieved. Imaging using custom phantoms (SJU and KWU) confirmed clear pattern reconstruction, demonstrating the potential of NiCo/β-Ga₂O₃ SBDs for low-dose, high-performance X-ray detection.

DOI：

https://doi.org/10.1016/j.surfin.2026.109657