Early stages of growth and nanostructure of Pb(Zr,Ti)O3 thin films observed by atomic force microscopy

We prepared lead zirconate-titanate (PZT) layers with different thicknesses on Au coated Si(100) and Si(111) wafers by pulsed laser deposition, using the same set of experimental conditions: a Nd-YAG laser, 1064 nm, 10 ns, 10 Hz, substrate temperature 370 degrees C, oxygen pressure 150 mTorr, laser fluence 25 J/cm(2), by varying the number of laser pulses. Different analysis put in evidence the crystallographic structure and chemical composition of films. Surface morphology was examined by atomic force microscopy (AFM). Analysis of films with very few atomic layers suggests that the growth proceeds by Volmer-Weber island-growth mechanism. Different geometrical, chemical and kinetic factors responsible for this type of growth are discussed. Comparative AFM analyses of surface roughness performed on films with different thickness allow for the study of the interface width evolution during the growth and to predict the conditions for obtaining films with a smooth surface. (C) 1998 Elsevier Science S.A. All rights reserved.