Growth evolution of ZnO films deposited by pulsed laser ablation

We study the surface morphology evolution of ZnO films grown by pulsed lase r deposition. Atomic force microscopy measurements show the existence of tw o growth regimes. Initially, the growth morphology is determined by shadowi ng effects due to the angular spreading of the plume in the 0.1 mbar oxygen working pressure. For longer deposition times a stepped pyramid-like struc ture is developed, whose roughening and coarsening behaviours are in agreem ent with those expected for growth systems with step-edge barriers.