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

Nanocomposite films formed by Cu nanocrystals (NCs) with sizes < 10 nm embe dded in an amorphous Al2O3 host have been grown by alternate pulsed-laser d eposition both in vacuum and in a buffer gas (Ar) up to pressures of 0.1 To rr. The dimensions, dimension distributions, and shape of the NC produced i n vacuum and in Ar up to pressures of 5 x 10(-3) Torr follow a similar tren d as a function of the Cu areal density. This allows us to conclude that th e nucleation and growth of the NC are dominated by processes occurring at t he 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, th e deposition rate decreases abruptly and a significant cant amount of the b uffer gas is incorporated into the host, thus leading to the formation of a porous material.