S0169
THE INTERFACIAL STRUCTURE AND THE PREFERRED ORIENTATION OF LAYERED
PEROVSKITE SrBi2Ta2O9 THIN FILMS GROWN ON THE
Pt ELECTRODE. Jeong Soo Lee*, Hyun Ha Kim*, Hyun Ja
Kwon*, Seshu B. Desu#, *LG Electronics
Research Center, 16, Woomyeon-dong, Seocho-gu, Seoul 137-140, Korea,
#Department of Materials Science and Engineering, Virginia
Polytechnic Institute and State University, Blacksburg, VA 24061-0237, USA
The influence of the Pt bottom electrode orientation on the growth of
ferroelectric SrBi2Ta2O9 (SBT) films was
interpreted in terms of the atomic matching at the interfaces. The symmetry of
SBT can be described as either an orthorhombic (SBTorth) or a
pseudo-tetragonal (SBTtet) structure. The preferred
orientations of the SBT layers were determined by comparing the experimentally
observed x-ray [[theta]]-2[[theta]] diffraction profiles with the
simulated powder diffraction one. A highly (001) prefer oriented
SBTtet film was grown when the Pt layer was mainly (001)
oriented. There are three kinds of SBTtet (001) plane
with different atomic configurations. All these atomic planes match pretty well
with the Pt (001) plane both energetically and crystallographically if the
following orientation relationship is satisfied; Pt (001) //
SBTtet (001) // SBTorth (001), Pt [
100] // SBTtet [100] // SBTorth [110], and
Pt [010] // SBTtet [010] //
SBTorth [
10]
The mismatches in the [100] and [010] directions of the
SBTtet are quite small (-0.74%). The (110) and (105)
SBTtet peaks were predominantly found when the Pt electrode
was (111) oriented. It was calculated that the Pt (111) plane exhibits a
relatively good matching with either one of the two kinds of
SBTtet (110) plane or the SBTtet (105)
plane. The following orientation relationships are proposed; i) Pt (111) //
SBTtet (110) // SBTorth (010), Pt [
10]
// SBTtet [1
0]
// SBTorth [100], and Pt [11
]
// SBTtet [00
]
// SBTorth [00
],
ii) Pt (111) // SBTtet (105) // SBTorth
(ll5), Pt [
10]
// SBTtet [010] // SBTorth [
10],
and Pt [11
]
// SBTtet [50
]
// SBTorth [55
].