ε-Ga2O3 Thin Film Avalanche Low-Energy X-Ray Detectors for Highly Sensitive Detection and Fast-Response Applications

Low-energy X-ray detectors are widely used in diverse areas, including medical diagnosis, space exploration, environmental monitoring, industrial inspection, and scientific research. Developing large area, highly sensitive, and fast low-energy X-ray detectors is challenging owing to material and device operation mechanism limitation. Herein, an epitaxial epsilon-Ga2O3 thin film over a large area (2 in.) is prepared by metal-organic chemical vapor deposition and applied in the efficient low-energy X-ray detectors. The detectors are highly sensitive to detecting low-energy X-rays owing to the high mass attenuation coefficients achieved in the low-energy X-ray range (1-30 keV). The avalanche multiplication mechanism in back-to-back Au-Ga2O3 Schottky diodes is explored to realize high carrier multiplication and photocurrent gain. The charge collection efficiency is improved by reducing the spacing gap of the fingers within the coplanar interdigitated Au electrodes in the film, thus achieving a high detection sensitivity of up to 1.9 x 10(4) mu CGy(air)(-1) cm(-2) for 30 keV X-ray. Furthermore, the epsilon-Ga2O3 thin films demonstrate high crystallization quality with low trap density and high breakdown voltage with a low noise current that enable their usage in applications requiring fast response time (e.g., 37 ms) and low detectable dose rate (e.g., 42.3 mu Gy(air) s(-1)).