Preparation and characterization of Pb(Nb,Ti)O3 thin films by metalorganic chemical vapor deposition

Lead niobium titanate, Pb(Nb,Ti)O-3, thin films were prepared on various substrates by metalorganic chemical vapor deposition from the Pb(C11H19O2)(2)-Nb(O . C2H5)(5)-Ti(O . i-C3H7)(4)-O-2 system. Polycrystalline films with (111) orientation and epitaxially grown films with c-axis orientation were deposited on the (111)Pt/Ti/SiO2(100)Si and PbTiO3/(111)Pt/Ti/SiO2/(100)Si substrates, and (100)SrRuO3//(100)LaAlO3 substrate, respectively, at 620 degrees C. Nb content in the film can be controlled only by changing the input gas flow rate of Nb(O . C2H5)(5) under the excess gas flow rate of Pb(C11H19O2)(2). The composition of the film was independent of the deposition temperature from 400 to 620 degrees C. The single phase of Pb(Nb,Ti)O-3 was deposited up to the Nb content of about 5 at % and pyrochlore phase was codeposited above this Nb content. Leakage current density decreased with the increasing Nb content in the film up to 6.5 at %. Coercive field (E-c) of the film was about 130 kV/cm and was independent of the Nb content and the kinds of substrates. On the other hand, the remanent polarization (Pr) of the film on the (111)Pt/Ti/SiO2/(100)Si substrate increased from 9 to 29 mu C/cm(2) with the increasing Nb content from 2.1 to 4.8 at %. Pr of the film on the (100)SrRuO3//(100)LaAlO3 substrate was smaller than those of the (111)Pt/Ti/SiO2/Si and PbTiO3/(111)Pt/Ti/SiO2/Si substrates. (C) 1999 American Institute of Physics. [S0021-8979(99)08820-9].