Thin films made of (100)/(001)-oriented Pb(Zr,Ti)O 3 (PZT) were deposited by liquid-delivery metalorganic chemical vapor deposition on Ir/MgAl 2 O 4 /SiO 2 /Si(100) substrates. For comparison, PZT thin films were also deposited on Ir/MgO(100) substrates. The X-ray scan spectra for the (202) reflections revealed that the PZT films have four-fold symmetry. It indicates that the PZT films were epitaxially grown as a cube-on-cube structure on both substrates. The switchable polarization (Q sw ) of the PZT capacitors on the silicon substrate was only 23 µC/cm 2 at 1.8 V; however, Q sw of PZT capacitors on MgO was 99 µC/cm 2 . In the case of PZT films deposited on silicon, the volume fraction of (001)-oriented domains (which contribute to polarization switching) was 15.1% (calculated from an XRD pattern). This result is due to the lower Q sw of PZT capacitors on silicon. By piezoresponse-force microscopy, switchable and unswitchable domains could be identified by imaging color contrast, namely, (001) and (100) domains, respectively. Consequently, domain distribution of the PZT film on a silicon substrate indicates that the (001) domain exists in the (100) domain matrix.