Formation of Ag and Au Plasmonic Nanoparticles by Ion Implantation in Ga$_2$O$_3$ thin films

Inês Freitas; Ana Sofia Sousa; Duarte Magalhães Esteves; Mamour Sall; Ângelo Rafael Granadeiro da Costa; Joana Madureira; Sandra Cabo Verde; Katharina Lorenz; Marco Peres

arXiv · 2603.23110

Formation of Ag and Au Plasmonic Nanoparticles by Ion Implantation in Ga$_2$O$_3$ thin films

Inês Freitas·Ana Sofia Sousa·Duarte Magalhães Esteves·Mamour Sall·Ângelo Rafael Granadeiro da Costa·Joana Madureira·Sandra Cabo Verde·Katharina Lorenz·Marco Peres

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Abstract

Gallium oxide (Ga$_2$O$_3$) is a wide-bandgap semiconductor with exceptional electrical and optical properties, making it a promising material for optoelectronic and sensing applications. In this work, we demonstrate for the first time the formation of plasmonic silver (Ag) and gold (Au) nanoparticles embedded in Ga$_2$O$_3$ thin films via ion implantation. Ga$_2$O$_3$ films deposited by RF sputtering on sapphire substrates were implanted with Ag or Au ions at 150 keV and a nominal fluence of 5 $\times$ 10$^{16}$ ions/cm$^2$, followed by thermal annealing between 200 and 700 °C. Rutherford backscattering spectrometry (RBS) measurements revealed saturation effects during implantation, resulting in lower incorporated fluences, as well as out-diffusion with post-implantation annealing. Transmission electron microscopy confirmed the formation of metallic nanoparticles with a distribution consistent with the metal profiles measured by RBS. Optical absorption measurements showed a pronounced localized surface plasmon resonance (LSPR) band in the Ag-implanted films, visible even in the as-implanted state and red-shifting with increasing annealing temperature, while Au-implanted films exhibited a distinct LSPR peak only after annealing at $\geq$500 °C. The observed LSPR shifts with annealing are attributed primarily to changes in the Ga$_2$O$_3$ matrix rather than a change in nanoparticle size. These results establish ion implantation as a viable approach for integrating plasmonic nanostructures into Ga$_2$O$_3$.

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Inês Freitas, Ana Sofia Sousa, Duarte Magalhães Esteves, Mamour Sall, Ângelo Rafael Granadeiro da Costa, Joana Madureira, Sandra Cabo Verde, Katharina Lorenz, Marco Peres. 2026-03-24. Formation of Ag and Au Plasmonic Nanoparticles by Ion Implantation in Ga$_2$O$_3$ thin films. https://arxiv.org/abs/2603.23110

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