Enhanced Sensitivity and Fast Response in α-Ga ₂ O ₃ X-ray Detectors Using Asymmetric Pt/Ti Electrodes

We report the performance of α-Ga2O3 metal–semiconductor–metal (MSM) X-ray detectors fabricated with symmetric (Ti/Ti) and asymmetric (Pt/Ti) electrode configurations. High-quality epitaxial α-Ga2O3 thin films were confirmed through XRD and TEM analysis, ensuring efficient charge transport and device stability. The asymmetric Pt/Ti device exhibited a more than three-orders-of-magnitude improvement in signal-to-noise ratio (SNR), faster transient response, and a significantly reduced decay time (∼0.1 s) compared with the symmetric Ti/Ti structure. Under −10 V bias, a sensitivity of 221 μC/Gy_air·cm2 was achieved at a dose rate of 1.09 mGy/s. Importantly, the Pt/Ti asymmetric contact configuration also enabled clear self-powered operation, exhibiting measurable sensitivity and SNR even at zero bias, highlighting its applicability in low-power or battery-free X-ray sensing. Compared with previously reported oxide semiconductor X-ray detectors, our device demonstrates advantages in crystalline quality, active-layer thinness, and fabrication cost. These results establish asymmetric electrode engineering as an effective approach for developing high-performance α-Ga2O3-based X-ray detectors suitable for low-dose, high-speed, and energy-efficient applications.