Perovskite Single-Phase Growth of Epitaxial Pb(Zn1/3Nb2/3)O3 Films by Alternative-Source-Gas-Introduced Metalorganic Chemical Vapor Deposition

Relaxor-type ferroelectric Pb(Zn1/3Nb2/3)O3 [PZN] films were prepared on (100), (110), (111)SrTiO3 and MgO substrates by metalorganic chemical vapor deposition (MOCVD). The dependences of the constituent phase of the deposited films on the sequence of gas introduction in the MOCVD and on the kinds of substrates and the orientation of the substrates were investigated systematically. Compared with continuous and pulsed sequences of source gas introduction, an alternative sequence of source gas introduction of the Pb and Zn+Nb, named alternative MOCVD, produces a higher phase purity of perovskite for film deposited on (100)MgO substrates. In addition, the phase-pure perovskite PZN film was first grown on (110) and (111)MgO substrates. This is due to the relatively smaller lattice mismatch between the perovskite PZN and the substrate than that between an impurity phase, pyrochlore, and substrates that exists when films are deposited on these substrates. This is the first reported deposition of the pyrochlore-free phase-pure epitaxial PZN films.