Flexible X-ray Detectors Based on Amorphous Ga₂O₃ Thin Films

Abstract

Ga2O3, as an emerging optoelectronic material, is very appealing for the detection of ionizing radiation because of its low cost, wide band gap (4.5–5.0 eV) and radiation hardness. In this work, a flexible X-ray detector using amorphous Ga2O3 (a-Ga2O3) thin film is demonstrated. The a-Ga2O3 thin film was deposited on polyethylene naphthalate (PEN) substrate with delicately control of the oxygen flux during the radio frequency (RF) magnetron sputtering process. Metal/semiconductor/metal-structured photodetectors with coplanar interdigital electrodes were fabricated on this a-Ga2O3 film. Temporal response measurements under X-ray illumination indicate that a larger photocurrent occurs on the film deposited with smaller oxygen flux. A model combined with theoretical calculation is proposed to explain the enhancement of the X-ray photoresponsivity, which involves the slowing down of the annihilation rate caused by the neutralization of more ionized oxygen vacancy (Vo) states. No significant degradation of the device performance under UV and X-ray radiation is observed after the flexibility test. This finding informs a novel way to design the flexible X-ray and other ionizing radiation detectors based on amorphous oxide materials.