Formation of Au fractal nanoclusters during pulsed laser deposition on highly oriented pyrolitic graphite

The topography of the Au submonolayer condensate formed by pulsed laser deposition (PLD) on pyrolitic graphite surface has been studied by scanning-tunneling microscopy (STM). PLD technique is characterized by an extremely high instantaneous deposition rate (up to 10²² atomscm^-2s^-1). The formation of Au fractal nanoclusters with D=1.33±0.08 was observed with STM. The mechanism driving the formation of fractal nanoclusters on the surface at high deposition rate is suggested to be the result of the interacting-adatom initial-states evolution in the system far from thermodynamic equilibrium. The geometrical structure of the forming nanoclusters depends critically on the rate at which atoms arrive at the surface as well as on its lattice symmetry.