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.

Boosted UV Photodetection Performance in Chemically Etched Amorphous Ga2O3 Thin‐Film Transistors

“…That will definitely influence the etching rate, considering the fact of their different V o defect densities. [ 8 ] The etching rates of S1 and S2 are plotted as a function of etching temperature in different TMAH concentrations in Figure S2 of the Supporting Information. The values are listed in Table S1 of the Supporting Information in detail.…”

“…[ 7 ] As is well known to all, PPC phenomenon occurs in most oxide semiconductor materials owing to the large quantity of oxygen vacancy ( V o ) defects and high density of trap states. [ 8,9 ]…”

Morphology and mobility as tools to control and unprecedentedly enhance X-ray sensitivity in organic thin-films

“…Noteworthy attention has to be paid in the comparison between the sensitivity values reported in the literature, since the units of measure and the types of normalization reported can be very different due to the plethora of organic materials/device geometries recently investigated for direct X-ray detection. In order to make a clear comparison between the sensitivity values presented in this work and the top sensitivities recently reported in the literature for organic 15,29 , hybrid organic/inorganic 4,6,8 , perovskite 38 , and inorganic for large-area X-ray detectors 28,39 , we summarize in Table 2 the sensitivity per unit area and per unit volume calculated using the same units of measurements.…”

Metal–Semiconductor–Metal Thin‐Film X‐Ray Detector Based on Halide Perovskites

“…Such fast rise and decay feature is a merit over some other semiconductor X‐ray detectors which need much longer time to reach maximum photocurrent. [ 13,25,26 ] It is worth noting that the precise measurement of rise and decay time of our devices was limited by our measurement setup. Usually, a much shorter response time can be seen in perovskite detectors.…”

“…Our X‐ray detector demonstrates low dark current and over 10 times better sensitivity than previous perovskite thin film X‐ray detector with a complicated multilayer structure. [ 9 ] The sensitivity is also better than thin‐film X‐ray detectors based on some nonperovskite materials such as Ga 2 O 3 and pentacene, [ 13,14 ] yet, it is still lower than the bulk perovskite X‐ray detectors due to insufficient absorption. The nonencapsulated device showed relatively high stability in air under continuous biasing, and the photocurrent remained unchanged after 3 months storage in dry cabinet.…”