Surface Roughness with Nanometer-Scale Ag Particles Generated by Ion Implantation

Surfaces of SiO2, Si3N4, Ta2O5 and glass were implanted
with Ag+ ions. Studies using X-ray diffraction (XRD) and atomic force microscopy
(AFM) show that the surface morphology is dominated by metallic silver
features consisting of regularly shaped, mostly spherical, Ag particles
spanning a size range from some nanometers to some 100 nm in diameter.
The particle size metrics, distribution, shape, and their density are shown
to be controlled by the process paramters ion dose, dose rate, and ion
energy. Adjusting the energy of the incident ions results in various degrees
of submerging into the substrate including exposed Ag features anchored
onto the surface or buried Ag particles overcoated by a thin layer of the
matrix material. The substrate material differs by its ability of stabilizing
the dispersion and blocking the Ag movement. Ta2O5 and glass substrates
provide more homogeneously dispersed Ag particles, much smaller in size
and regularly shaped compared to SiO2 and Si3N4 substrate systems. Potential
application refers to surface enhanced Raman scattering.