Orthorhombic undoped κ-Ga2O3 epitaxial thin films for sensitive, fast, and stable direct X-ray detectors

Photoelectronic properties of orthorhombic undoped κ-Ga2O3 epitaxial thin films, grown on sapphire substrates by metal–organic vapour phase epitaxy, were evaluated under X-ray irradiation (CuKα line, 8.05 keV) for the first time. Photoresponse linearity at low dose-rates (varying in the 10–200 μGy s−1 range), and excellent detection sensitivity (up to 342.3 μC Gy−1 cm−3), were demonstrated even at very low applied electric fields (down to 0.001 V μm−1). Photocurrent rise time was evaluated to be