Controllable surface-plasmon resonance in engineered nanometer epitaxial silicide particles embedded in silicon

Epitaxial ${\mathrm{CoSi}}_2$ particles in a single-crystal silicon matrix are grown by molecular-beam epitaxy using a technique that allows nanometer control over particle size in three dimensions. These composite layers exhibit resonant absorption predicted by effective-medium theory. Selection of the height and diameter of disklike particles through a choice of growth conditions allows tailoring of the depolarization factor and hence of the surface-plasmon resonance energy. Resonant absorption from 0.49 to 1.04 eV (2.5 to 1.2 μm) is demonstrated and shown to agree well with values predicted by the Garnett theory using the bulk dielectric constants for ${\mathrm{CoSi}}_2$ and Si.