In situ <inline-formula> <tex-math notation="LaTeX">\textit{I}</tex-math> </inline-formula> <inline-formula> <tex-math notation="LaTeX">-</tex-math> </inline-formula> <inline-formula> <tex-math notation="LaTeX">\textit{V}</tex-math> </inline-formula> and <inline-formula> <tex-math notation="LaTeX">\textit{C}\!\!-\!\!\textit{V}</tex-math> </inline-formula> measurements were performed during the 120 MeV Au<inline-formula> <tex-math notation="LaTeX">^{9+}</tex-math> </inline-formula> ion irradiation on the Pt/Al<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>/<inline-formula> <tex-math notation="LaTeX">\beta </tex-math> </inline-formula>-Ga<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>, metal-oxide-semiconductor capacitors (MOSCAPs), to comprehend the swift heavy ion (SHI)-induced effects at the interface and in the device performance. At a maximum fluence of 2 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{\text{12}}</tex-math> </inline-formula> ions/cm<inline-formula> <tex-math notation="LaTeX">^{\text{2}}</tex-math> </inline-formula>, the <inline-formula> <tex-math notation="LaTeX">\textit{I}-\!\textit{V}</tex-math> </inline-formula> data showed a rise in the reverse leakage current by four orders of magnitude compared to the pristine device. The trap level (below the conduction band of Al<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}\text{)}</tex-math> </inline-formula> from Poole-Frenkel emission exhibits a variation from <inline-formula> <tex-math notation="LaTeX">\sim</tex-math> </inline-formula>1.1 to 0.91 eV. The conduction band offset <inline-formula> <tex-math notation="LaTeX">{\text{(}\phi }_{\textit{B}}\text{) }</tex-math> </inline-formula> of Al<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>/<inline-formula> <tex-math notation="LaTeX">\beta </tex-math> </inline-formula>-Ga<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> changes from 1.48 to 1.25 eV as estimated under the Fowler-Nordheim tunneling mechanism. In situ <inline-formula> <tex-math notation="LaTeX">\textit{C}\!\!-\!\!\textit{V}</tex-math> </inline-formula> measurements show a significant shift in the flat band voltages and increased oxide in the border and interface due to charge trapping. The X-ray photoelectron spectroscopy (XPS) measurements of Al 2p and O 1s core levels revealed the pre-existing oxygen defects in Al<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>, which increase with fluence. The deconvoluted peaks of Al 2p at 74.6 eV designated to Al-sub oxide and the O 1s peak variation in the FWHM signifies the increase in the O defects. Cross-sectional transmission electron microscopy (XTEM) measurements on the irradiated device (at 2 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{\text{12}}</tex-math> </inline-formula> ions/cm<inline-formula> <tex-math notation="LaTeX">^{\text{2}}\text{)}</tex-math> </inline-formula> revealed a modulated interface of Al<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>/<inline-formula> <tex-math notation="LaTeX">\beta </tex-math> </inline-formula>-Ga<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> and the formation of an interlayer of <inline-formula> <tex-math notation="LaTeX">\sim</tex-math> </inline-formula>4 nm Al<inline-formula> <tex-math notation="LaTeX">_{\textit{x}}</tex-math> </inline-formula>Ga<inline-formula> <tex-math notation="LaTeX">_{\textit{y}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\textit{z}}</tex-math> </inline-formula>. The scanning transmission electron microscope (STEM)-based high-angle annular dark-field imaging (HAADF) energy-dispersive X-ray spectroscopy (EDS) mapping revelation and the depth profiles of XPS data confirm the formation of an Al<inline-formula> <tex-math notation="LaTeX">_{\textit{x}}</tex-math> </inline-formula>Ga<inline-formula> <tex-math notation="LaTeX">_{\textit{y}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\textit{z}}</tex-math> </inline-formula> interlayer.