Plasma-induced size reduction in gold nanoclusters embedded in a dielectric matrix

Sandwich structures of silicon-nitride/gold/silicon-nitride with approximate thickness of 40 nm were fabricated by means of inductively-coupled remote plasma enhanced chemical vapor deposition and sputtering. In an intermediate step, nanostructure gold was subject to different surface plasma treatments, varying the plasma treatment time as well as the plasma atmosphere. The resulting structures were studied by high resolution transmission electron microscopy and Rutherford backscattering. As a consequence of plasma treatments, the gold nanoparticles mean size decreases, the particle areal distributions become narrower and the particle shapes evolve from island-like to near spherical symmetry. Oxygen plasma-etch of gold nanoparticles was observed.