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Dielectric multilayers impact on radiation-induced charge accumulation in highly sensitive oxide field effect transistors
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Resumo(s)
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.
Descrição
Funding Information: The authors acknowledge the funding by the EU—NextGenerationEU—with funds made available by the National Recovery and Resilience Plan (NRRP) Mission 4, Component 1, Investment 4.1 (MD 351/2022)—NRRP Research. This work also received funding from the European Community’s Horizon Europe program (ERC-POC FLETRAD, Grant Agreement No. 101082283) and from National Funds through the FCT —Fundação para a Ciência e a Tecnologia, I.P.), Project Nos. LA/P/0037/2020, UIDP/50025/2020, and UIDB/50025/2020 of the Institute of Nanostructures, Nanomodelling and Nanofabrication—i3N. We would also like to acknowledge the Portuguese Foundation for Science and Technology, under the scope of doctoral Grant Nos. DFA/BD/8335/2020 and 2022.09516.BD, for the support. Publisher Copyright: © 2024 Author(s).
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General Materials Science General Engineering