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The study of optical and plasmonic properties of structures is an important step in the development of substrates for surface-enhanced Raman scattering (SERS) applications. In this work, structures based on a disordered array of hemispherical silver nanoparticles (AgNPs) on a single-crystal silicon (c-Si) substrate are studied. A simple and reproducible method is proposed in which an Ag island film obtained by chemical reduction of AgNO 3 is transformed after annealing at 350 °C into an array of hemispherical AgNPs on a thin SiO 2 layer. The average radii of AgNPs range from 30 to 130 nm, which can be varied due to the concentration of AgNO 3 in the initial deposition solution. Numerical calculations of the scattering, absorption, and extinction cross-sections are used to determine the positions of the localized surface plasmon resonance (LSPR) multipoles depending on the hemispherical AgNP size. The splitting of the LSPR dipole is found in the reflection spectra at oblique angles of incidence for p-polarization of light, which indicates the prolate shape of the hemispherical AgNPs. Finally, SERS shows reliable detection of 10−7 M (crystal violet) with the enhanced factor ∼ 6.2 × 10 5 and the relative standard deviation of signal ∼ 10 %. These studies suggest that hemispherical AgNPs on a SiO 2 @c-Si are promising candidates for detecting triphenylmethane dyes. [Display omitted] • SERS substrates based on hemispherical AgNPs on SiO 2 @c-Si have been fabricated. • FDTD calculations were used to determine LSPR multipoles as a function of AgNP size. • Splitting of the LSPR in the reflection spectra of p-polarized light was found. • Prolate shape of the AgNPs were confirmed by SEM method and optical investigations. • SERS substrates showed reliable CV detection of 10−7 M with EF ∼ 6.2 × 10 5 and RSD ∼ 10 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • SiO 2 /embedded AgPs/c-Si and embedded AgPs/c-Si hybrid structures were successfully fabricated as SERS substrates. • The high performance of SERS is due to the sharp corners of the embedded AgPs. • The SERS substrate provides high sensitivity for the detection of the organic dye. • The dependences of the position of the low-frequency LSPR as a function of the structures morphology are calculated. The formation of hybrid structures for creating sensitive sensors is a difficult task. In this study, we developed a facile technique of semiconductor technology to fabricate hybrid structures based on SiO 2 /embedded Ag/Si and embedded Ag/Si for a surface-enhanced Raman scattering. Herein, our hybrid structures were created in one technological cycle, which consists of the reduction of silver nitrate salt from a solution on the silicon surface and subsequent high-temperature annealing at 1000 °C. In addition, it allows not only to preserve the plasmonic properties of Ag particles on the Si surface but also to protect them from further external influences by coating them with a SiO 2 layer. Also, the basis for creating such hybrid structures is the performed numerical calculations of the position of a localized surface plasmon resonance as a function of the geometry of structures. Furthermore, the theoretical full-wave electromagnetic modeling of Raman scattering in an embedded Ag/Si structure showed the presence of enhancement regions "hot spots" at sharp corners with a maximum enhancement factor of 106. Finally, surface-enhanced Raman scattering spectroscopy of such structures showed reliable detection of the methyl orange from an aqueous solution at a concentration of 10-5 M. [ABSTRACT FROM AUTHOR]