Purpose: We investigated the characteristics of radiation-induced current in nano-porous pellet and thin-film anodized tantalum exposed to kVp X-ray beams. We aim at developing a large area (≫cm2) thin-film radiation sensor for medical, national security and space applications. Methods: Large area (few cm2) micro-thin Ta foils were anodized and coated with a counter electrode made of conductive polymer. In addition, several types of commercial electrolytic porous tantalum capacitors were assembled and prepared for irradiation with kVp X-rays. We measured dark current (leakage) as well as transient radiation-induced currents as a function of external voltage bias. Results: Large transient currents (up to 50 nA) under X-ray irradiation (dose rate of about 3 cGy/s) were measured in Ta2O5 capacitors. Small nano-porous Ta and large-area flat Ta foil capacitors show similar current–voltage characteristic curve after accounting for different X-ray attenuation in capacitor geometry. The signal is larger for thicker capacitor oxide. A non-negligible signal for null external voltage bias is observed, which is explained by fast electron production in Ta foils. Conclusions: Anodized tantalum is a promising material for use in large-area, self-powered radiation sensors for X-ray detection and for energy harvesting.

中文翻译：

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阳极氧化 Ta2O5 中的 X 射线感应电流：走向大面积薄膜传感器

目的：我们研究了暴露在 kVp X 射线束下的纳米多孔颗粒和薄膜阳极氧化钽的辐射感应电流特性。我们的目标是开发用于医疗、国家安全和空间应用的大面积（≫cm2）薄膜辐射传感器。方法：对大面积（几平方厘米）超薄钽箔进行阳极氧化，并涂上由导电聚合物制成的对电极。此外，还组装了几种商业电解多孔钽电容器并准备用于 kVp X 射线照射。我们测量了暗电流（泄漏）以及瞬态辐射感应电流作为外部电压偏置的函数。结果：在 X 射线照射（剂量率约 3 cGy/s）下，Ta2O5 电容器测量到大瞬态电流（高达 50 nA）。考虑到电容器几何形状中不同的 X 射线衰减后，小型纳米多孔 Ta 电容器和大面积扁平 Ta 箔电容器表现出相似的电流-电压特性曲线。电容器氧化层越厚，信号越大。观察到零外部电压偏置的不可忽略的信号，这是通过钽箔中快速电子产生来解释的。结论：阳极氧化钽是一种很有前途的材料，可用于大面积、自供电辐射传感器，用于 X 射线检测和能量收集。