Composition Dependences Of Crystal Structure And Electrical Properties Of Epitaxial Pb(Zr,Ti)O-3 Films Grown On Si And Srtio3 Substrates

{100}-oriented Pb(Zr-x, Ti1-x)O-3 (PZT) thin films of approximately 2 mu m thickness and Zr/(Zr + Ti) ratios of 0.39-0.65 were epitaxially grown on (100)(c)SrRuO3//(100)SrTiO3 (STO) and (100)(c)SrRuO3//(100)(c)LaNiO3//(100)CeO2//(100)YSZ//(100) Si (Si) substrates having different thermal expansion coefficients by pulsed metal-organic chemical vapor deposition (MOCVD). The effects of Zr/(Zr + Ti) ratio and type of substrate on the crystal structure and dielectric, ferroelectric and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that both films changed from having a tetragonal symmetry to rhombohedral symmetry through the coexisting region with increasing Zr/(Zr + Ti) ratio. This region showed the Zr/(Zr + Ti) ratios of 0.45-0.59 for the films on the STO substrates that were wider than the films on the Si substrates. Saturation polarization values were minimum at approximately Zr/(Zr + Ti) = 0.50 for the films on the STO substrates, and no obvious Zr/(Zr + Ti) ratio dependence was detected in the films on the Si substrates. On the other hand, the maximum field-induced strain values measured by scanning force microscopy at approximately Zr/(Zr + Ti) = 0.50 at 100 kV/cm were about 0.5 and 0.1% in the films on the Si and STO, respectively. (C) 2016 The Japan Society of Applied Physics