Switching of ferroelectric polarization in epitaxial BaTiO₃ films on silicon without a conducting bottom electrode.
Epitaxial growth of SrTiO₃ on silicon by molecular beam epitaxy has opened up the route to the integration of functional complex oxides on a silicon platform. Chief among them is ferroelectric functionality using perovskite oxides such as BaTiO₃. However, it has remained a challenge to achieve ferroelectricity in epitaxial BaTiO₃ films with a polarization pointing perpendicular to the silicon substrate without a conducting bottom electrode. Here, we demonstrate ferroelectricity in such stacks. Synchrotron X-ray diffraction and high-resolution scanning transmission electron microscopy reveal the presence of crystalline domains with the long axis of the tetragonal structure oriented perpendicular to the substrate. Using piezoforce microscopy, polar domains can be written and read and are reversibly switched with a phase change of 180°. Open, saturated hysteresis loops are recorded. Thus, ferroelectric switching of 8- to 40-nm-thick BaTiO₃ films in metal-ferroelectric-semiconductor structures is realized, and field-effect devices using this epitaxial oxide stack can be envisaged.
1] IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598, USA [2].
Catherine
C
Dubourdieu
John
J
Bruley
Thomas M
TM
Arruda
Agham
A
Posadas
Jean
J
Jordan-Sweet
Martin M
MM
Frank
Eduard
E
Cartier
David J
DJ
Frank
Sergei V
SV
Kalinin
Alexander A
AA
Demkov
Vijay
V
Narayanan