Growth of Pb(Ti,Zr)O3 thin films by metal-organic molecular beam epitaxy

Single-crystal Pb(ZrxTi1−x)O3 thin films have been grown on (0 0 1) SrTiO3 and SrTiO3:Nb substrates by molecular beam epitaxy using metal-organic source of Zr and two different sources of reactive oxygen—RF plasma and hydrogen-peroxide sources. The same growth modes and comparable structural properties were observed for the films grown with both oxygen sources, while the plasma source allowed higher growth rates. The films with x up to 0.4 were single phase, while attempts to increase x beyond gave rise to the ZrO2 second phase. The effects of growth conditions on growth modes, Zr incorporation, and phase composition of the Pb(ZrxTi1−x)O3 films are discussed. Electrical and ferroelectric properties of the Pb(ZrxTi1−x)O3 films of ~100 nm in thickness grown on SrTiO3:Nb were studied using current–voltage, capacitance–voltage, and polarization–field measurements. The single-phase films show low leakage currents and large breakdown fields, while the values of remanent polarization are low (around 5 μC/cm2). It was found that, at high sweep fields, the contribution of the leakage current to the apparent values of remanent polarization can be large, even for the films with large electrical resistivity (∼108–109 Ω cm at an electric filed of 1 MV/cm). The measured dielectric constant ranges from 410 to 260 for Pb(Zr0.33Ti0.67)O3 and from 313 to 213 for Pb(Zr0.2Ti0.8)O3 in the frequency range from 100 to 1 MHz.