Investigation of Piezoelectricity and Curie Temperature of Pb(Mg1/3, Nb2/3)O3–PbTiO3 Epitaxial Thin Film on Si Prepared by Sputter Deposition With Fast Cooling

This paper reports on an abnormally high Curie temperature (T
_c
) of a Pb(Mg
_1/3
, Nb
_2/3
)O
₃
-PbTiO
₃
(PMN-PT) epitaxial thin film on Si prepared by sputter deposition with fast cooling. This deposition method was previously applied to Pb(Mn, Nb)O
₃
-Pb(Zr, Ti)O
₃
, and a c-axis-oriented epitaxial film with high T
_c
was obtained. Using the same method, a crackfree 2-μm-thick PMN-PT thin film was epitaxially grown on a Si substrate covered with buffer layers. The piezoelectricity, |e
₃₁
, f|, was as large as 18~19 C/m
²
under an electric field ranging from 25 to 75 kV/cm. The temperature characteristics of the dielectric constant and crystalline structure were significantly different from those of a bulk single crystal of PMN-PT, and suggested T
_c
higher than 500 °C. The enhanced T
_c
was possibly caused by thermally induced compressive strain received from the Si substrate. This approach can be an effective method for breaking the well-known tradeoff relationship between piezoelectricity and T
_c
of a piezoelectric thin film.