Radiation dosimetry is crucial in many fields where the exposure to ionizing radiation must be precisely controlled to avoid health and environmental safety issues. Among solid state detectors, we recently demonstrated that Radiation sensitive OXide Field Effect Transistors (ROXFETs) are excellent candidates for personal dosimetry thanks to their fast response and high sensitivity to x rays. These transistors use indium–gallium–zinc oxide as a semiconductor, combined with a dielectric based on high-permittivity and high-atomic number materials. Here, we present a study on the ROXFET gate dielectric fabricated by atomic layer deposition, where we compare single- and multi-layer structures to determine the best-performing configuration. All the devices show stable operational parameters and high reproducibility among different detectors. We identified an optimized bi-layer dielectric structure made of tantalum oxide and aluminum oxide, which demonstrated a sensitivity of (63 ± 2) V/Gy, an order of magnitude larger than previously reported values. To explain our findings, we propose a model identifying the relevant charge accumulation and recombination processes leading to the large observed transistor threshold voltage shift under ionizing radiation, i.e., of the parameter that directly defines the sensitivity of the device.

中文翻译：

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电介质多层对高灵敏度氧化物场效应晶体管中辐射引起的电荷积累的影响

辐射剂量测定在许多领域至关重要，必须精确控制电离辐射的暴露以避免健康和环境安全问题。在固态探测器中，我们最近证明，辐射敏感氧化物场效应晶体管 (ROXFET) 因其对 X 射线的快速响应和高灵敏度而成为个人剂量测定的绝佳候选者。这些晶体管使用氧化铟镓锌作为半导体，并结合基于高介电常数和高原子序数材料的电介质。在这里，我们提出了一项关于通过原子层沉积制造的 ROXFET 栅极电介质的研究，其中我们比较单层和多层结构以确定最佳性能的配置。所有装置均表现出稳定的工作参数和不同探测器之间的高再现性。我们确定了一种由氧化钽和氧化铝制成的优化双层介电结构，其灵敏度为 (63 ± 2) V/Gy，比之前报道的值大一个数量级。为了解释我们的发现，我们提出了一个模型，该模型可识别相关的电荷积累和重组过程，导致在电离辐射下观察到较大的晶体管阈值电压偏移，即直接定义器件灵敏度的参数。