Resputtering and morphological changes of Au nanoparticles in nanocomposites as a function of the deposition conditions of the oxide capping layer

A multilayer nanocomposite consisting of Au nanoparticles separated by layers of amorphous Al2O3 was prepared by pulsed laser deposition. The laser energy density used to deposit the Al2O3 layers was varied to investigate the effects on the resulting microstructure. When Al2O3 is deposited on the Au it results in resputtering and interfacial mixing of the Au nanoparticles into the Al2O3 matrix being deposited onto them. This leads to a reshaping of the nanoparticles, elongating them in the growth direction and in some cases forming cavities in the nanoparticles. These effects become more pronounced with increasing laser energy density. The high kinetic energies of the species involved also result in implantation of Au into the Al2O3 where it forms nanoparticles of about 1 nm mean diameter.