Highly sensitive surface acoustic wave x-ray detector based on piezoelectric ε -phase gallium oxide film

ε-phase gallium oxide (ε-Ga2O3), a wide-bandgap semiconductor with intrinsically high resistivity, radiation tolerance, and piezoelectric properties, enables the integration of surface acoustic wave (SAW) operation with x-ray detection, providing a frequency-domain sensing mechanism with enhanced noise immunity. In this work, a single-port resonant SAW x-ray detector based on an ε-Ga2O3 thin film grown on sapphire is demonstrated. The device employs submicrometer interdigital transducers to achieve GHz-frequency operation, exhibiting a Rayleigh-mode resonance at 1.35 GHz. Over x-ray dose rates ranging from 191 to 1149 mGy/s, both the resonance frequency shift and attenuation exhibit monotonic, theoretically consistent behavior governed by the acoustoelectric effect, enabling dual-parameter sensing of radiation-induced changes in conductivity. A high sensitivity of 1.58 ppm/Gy is achieved at 1149 mGy/s. The device also shows stable on–off switching and repeatable responses. Furthermore, compatibility with radio frequency systems makes the proposed device promising for passive wireless sensing and high-capacity multiplexed radiation detection applications.