The aim of this study is to investigate the structural transformations of erbium oxide (Er₂O₃) dielectric which can be used as a sensitive region in the new generation RadFET radiation sensors under a high gamma dose. The Er₂O₃ film was grown on n-type Si (100) by RF magnetron sputtering and film thickness was measured as 118 nm. The samples were irradiated by a ⁶⁰Co radioactive source with the doses of 1 kGy, 25 kGy, and 50 kGy. The crystal structure samples were analysed by the X-ray diffraction method. The variation in the bond properties of the as-deposited Er₂O₃ film was investigated by X-ray photoelectron spectroscopy. The pre-irradiation Er₂O₃ film demonstrated an amorphous structure, and the peaks belonging to the cubic phase were observed after irradiation, their density increasing with increasing the dose. The Er 4d spectra of the Er₂O₃/Si films were two fitted peaks indicating Er-Er and Er-O bonds, except for the interface. The binding energy shifted to higher energies with increasing the depth from due to possible ErSiO_x formation at the interface. The Si-O/Er-O and M/O ratios change with the applied dose and film depth.

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