Optical studies of amorphous Ge nanostructures in Al 2 O 3 produced by pulsed laser deposition

Thin films with embedded amorphous Ge nanostructures are characterised by in-situ and post-deposition techniques in order to study their size-dependent properties. The films are multilayer structures in which Ge nanostructured layers with effective thickness are separated by amorphous aluminium oxide layers (Al2O3). During deposition in-situ reflectivity measurements are used to achieve information on the amount of Ge deposited and on the Al2O3 coverage. The effective optical properties of the films were obtained from spectroscopic ellipsometry measurement analysis. Our results suggest a topological evolution of the Ge nanostructures as a function of the Ge content and the existence of size-dependent quantum confinement effects in the nanostructures.