Sequential growth of Ag nanoparticles on ripple-patterned Si: Insights from GISAXS/GIWAXS and MD simulations

The spatial arrangement and morphology of metallic NPs critically influence performance in plasmonic and spintronic applications. Substrate topography, especially ion-irradiation induced ripple patterns, strongly affects NP nucleation, growth dynamics, and final geometry. For Ag-NPs on nanoripple silicon, assembly depends on deposition direction because the morphology is intrinsically asymmetric; GISAXS confirms one slope is steeper. Single-direction deposition promotes uniaxial, ellipsoidal Ag-NPs aligned in the ripple direction, whereas sequential deposition yields truncated NPs with more uniform spacing. GIWAXS indicates an FCC structure with preferred (111) and (200) orientations; d-spacings remain consistent at 0° and 90°, indicating structural stability. Molecular dynamics simulations support these findings, showing single-sided flux favors tilted, elongated growth, while sequential flux forms near-spherical NPs near ridge regions and distributes them across slopes. Together, experiment and simulation establish how coupling surface asymmetry with deposition geometry governs NP shape, ordering, and crystallinity, offering a substrate-guided route to engineering isotropic assemblies.