Vacuum versus gas environment felt the synthesis of nanocomposite films by pulsed-laser deposition

Nanocomposite films formed by Cu nanocrystals (NCs) with sizes < 10 nm embedded in an amorphous Al2O3 host have been grown by alternate pulsed-laser deposition both in vacuum and in a buffer gas (Ar) up to pressures of 0.1 Torr. The dimensions, dimension distributions, and shape of the NC produced in vacuum and in Ar up to pressures of 5 x 10(-3) Torr follow a similar trend as a function of the Cu areal density. This allows us to conclude that the nucleation and growth of the NC are dominated by processes occurring at the substrate surface rather than in the gas phase. For Ar pressures greater than or equal to 5 x 10(-2) Torr, the anisotropy of the NC is enhanced, the deposition rate decreases abruptly and a significant cant amount of the buffer gas is incorporated into the host, thus leading to the formation of a porous material.