Effect of oxygen pressure upon composition variation during chemical vapor deposition growth of lead titanate films from tetraethyl lead and titanium tetraisopropoxide

Lead titanate (PbTiO3) films have been prepared from mixtures of tetraethyl lead (Pb(C2H5)(4)), titanium tetrasiopropoxide (Ti(i-OC3W7)(4)) and oxygen (O-2) by a low-pressure chemical vapor deposition (LPCVD) reactor. The effects of O-2 to the film growth including growth rate, crystalline property, and composition are investigated. Without adding O-2, the film formed at 823 K shows only TiO2 XRD diffraction pattern, whereas stoichiometric PbTiO3 is formed after adding 1 vol.% of O-2. Based on RBS composition analyses, increasing surplus O-2 concentration not only decreases the amount ratio of Pb but also causes concentration profile of Pb in the films. The deviation of Pb composition is reduced by raising the substrate temperature up to 873 K. A thermodynamic calculation of the stability domain of the Pb-O system suggests that the formation of high valence lead oxides having high volatility during film deposition is responsible for the Pb-deficient phenomenon in this CVD process. (C) 2000 Elsevier Science B.V. All rights reserved.