Investigation of low to high-dose gamma-ray (γ-ray) radiation effects on indium-zinc-oxide (IZO) thin film transistor (TFT)

This paper investigates the impact of gamma-ray (γ-ray) radiation at doses of 100 krads and 1,000 krads on amorphous indium-zinc-oxide (IZO) thin-film transistors (TFTs). The IZO channel's properties are analyzed using X-ray photoelectron spectroscopy (XPS) before and after radiation. Following 100 krads exposure, the oxygen vacancy (VO) peak in the IZO channel increases from 41.8 % to 59.4 % due to the generation of electron-hole pairs. Additionally, the threshold voltage of the IZO TFT negatively shifts from 10.1 V to 5.5 V due to positive charges in the gate oxide layer. Following exposure to 1,000 krads gamma-ray radiation, the threshold voltage of 8.8 V is similar to that of 9.8 V for the non-irradiated TFT. Remarkably, the subthreshold swing (SS) remains unchanged, while the maximum transconductance (gm,max) is improved by 10.0 % and effective mobility (µFE) by 6.1 %. These enhancements result from the diffusion of indium, zinc, and oxygen into the gate oxide layer thanks to the self-heating effect at a dose of 1,000 krads. Based on the results, our findings indicate the IZO TFT shows a significant potential for a radiation-hardness electronic device in harsh environments.