An XPS study of the nucleation and growth behavior of an epitaxial Pb(Zr,Ti)O-3/MgO(100) thin film prepared by MOCVD

The chemical states and the composition of the surface of the epitaxially-g rown lead zirconium titanate (PZT) thin films, prepared by MOCVD on an as-c leaved MgO(100) substrate, were studied by X-ray photoelectron spectroscopy (XPS). At our deposition rate (4.3 nm/min), lateral growth occurred at 20- s depositions, and three-dimensional growth occurred after 30-s depositions . Between the 10 and 40-s depositions, the XPS spectra of Pb (4f) had shoul ders at 141 and 136 eV, which strongly suggested that metal Pb co-exists wi th PZT in the lateral growth region. The binding energy of C (Is) was almos t constant, irrespective of the deposition time (deposition mode). However, the binding energies of Pb (4f), Zr (3d), Ti (2p), and O (Is) showed a ten dency that binding energy in the lateral growth mode was slightly higher th an in the three-dimensional growth mode. The surface atomic ratio Zr/(Zr Ti) was constant between 10 and 1800 s; on the other hand, the surface atom ic ratio Pb/(Pb + Zr + Ti) was almost stoichiometric at the initial stage o f deposition, increased with deposition time, and turned out to be constant above 100 s, with a value of Pb/(Pb + Zr + Ti)= 0.6. (C) 2000 Elsevier Sci ence S.A. All rights reserved.