Ion beam sputtered ultra-thin and nanostructured Ag films for surface plasmon applications

The growth of ultra-thin (10−17 nm) Ag films by ion beam sputtering with controlled morphology suitable for surface plasmon applications is demonstrated. A growth rate of 0.02 nm/s, by employing Ar ion energies as low as 150 eV, is achieved. These conditions result in a surface morphology that consists of oblate particles of size 10–30 nm, depending on the ion energy, with surface roughness of 1–3 nm. The aspect ratio of the grains decreases from 77 to 20 with increase in incident ion energy. The morphology-induced changes are manifested in the shift of the surface plasmon resonance peak from 440 to 480 nm.