Structural studies of Ag nanocrystals embedded in amorphous Al2O3 grown by pulsed laser deposition

Thin films consisting of layers of Ag nanocrystals (NCs) embedded in amorphous Al2O3 were grown by pulsed laser deposition. High-resolution electron microscopy was used to characterize the structure of the films. The growth kinetics of the NCs were studied by varying the Ag content of the films between 0.8 and 12.4OE10 exp 15 atoms/sq cm which produced NCs with average diameters of between 1.1 and 9.6 nm. At low Ag content, the NCs have a spherical in-plane shape with a narrow size distribution but they become more elongated with a broader size distribution as the Ag content increases due to coarsening and coalescence of the NCs. Underneath each layer of NCs, there is a continuous layer of what is believed to be Ag implanted into the amorphous Al2O3 due to the high kinetic energy, of the order of 100 eV, of the Ag species produced during laser ablation. (Author)