Passive radiofrequency x-ray dosimeter tag based on flexible radiation-sensitive oxide field-effect transistor

Open Access

Abstract

This work was funded by the European Union (EU) seventh Framework Programme (FP7/2007-2013) under grant agreement no. 611070, "Integrated Flexible Photonic Sensors System (iFLEXIS)" and by the EU Horizon 2020 Programme (European Research Council) under grant agreement no. 716510, 'Transparent and flexible electronics with embedded energy harvesting based on oxide nanowire devices (TREND)" projects. Further funding is acknowledged from FEDER funds through the COMPETE 2020 Programme and National Funds through the Portuguese Foundation for Science and Technology (FCT) under project no. UID/CTM/50025/2013. ; Distributed x-ray radiation dosimetry is crucial in diverse security areas with significant environmental and human impacts such as nuclear waste management, radiotherapy, or radioprotection devices. We present a fast, real-time dosimetry detection system based on flexible oxide thin-film transistors that show a quantitative shift in threshold voltage of up to 3.4 V/gray upon exposure to ionizing radiation. The transistors use indium-gallium-zinc-oxide as a semiconductor and a multilayer dielectric based on silicon oxide and tantalum oxide. Our measurements demonstrate that the threshold voltage shift is caused by the accumulation of positive ionization charge in the dielectric layer due to high-energy photon absorption in the high-Z dielectric. The high mobility combined with a steep subthreshold slope of the transistor allows for fast, reliable, and ultralow-power readout of the deposited radiation dose. The order-of-magnitude variation in transistor channel impedance upon exposure to radiation makes it possible to use a low-cost, passive radiofrequency identification sensor tag for its readout. In this way, we demonstrate a passive, programmable, wireless sensor that reports in real time the excess of critical radiation doses. ; publishersversion ; published