# X-ray Induced Electric Currents in Anodized Ta2O5: Towards a Large-Area Thin-Film Sensor

## TL;DR

This paper explores using anodized tantalum as a self-powered X-ray sensor for medical, security, and space applications.

## Contribution

The study demonstrates large transient currents in anodized tantalum under X-ray irradiation, suggesting its potential for large-area sensors.

## Key findings

- Large transient currents (up to 50 nA) were observed in Ta2O5 capacitors under X-ray irradiation.
- Signal strength increases with thicker capacitor oxide and is detectable even at zero external voltage bias.
- Nano-porous and flat Ta capacitors show similar current–voltage characteristics when adjusted for X-ray attenuation.

## Abstract

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.