Hard x-ray detection by using β-Ga2O3 devices fabricated through radiofrequency sputtering

This study examined the deposition, characteristics, and device performance of β-Ga2O3 thin films optimized for high-energy x-ray detection. β-Ga2O3 thin films were deposited through radiofrequency magnetron sputtering under various working pressures, oxygen flow rates, and substrate temperatures. Structural analysis through x-ray diffraction and Raman spectroscopy were confirmed. The deposition under a working pressure of 3 mTorr, an oxygen flow rate of 2 cubic centimeters per minute at standard temperature and pressure, and a substrate temperature of 600 °C exhibited the highest crystallinity and had well-defined (400), (020), and (3¯12) orientations. Atomic force microscopy and scanning electron microscopy revealed that films deposited under the above-mentioned parameters had the smoothest surface and uniform thickness. Optical characterization showed that deposition conditions significantly influenced the film’s bandgap and transmittance. The integration of β-Ga2O3 with an indium gallium zinc oxide (IGZO) charge transport layer substantially improved device performance. Peak photocurrents of 5.6 μA and 17.34 nA under 265-nm ultraviolet illumination and 50 keV x-ray illumination, respectively, were achieved. The device with an IGZO charge transport layer exhibited high sensitivity (493 μC/mGy cm2) and an excellent signal-to-noise ratio (3459.3) under 50 keV x-ray illumination.