BaTiO3 waveguides have been fabricated on r-cut sapphire single crystals us
ing an epitaxial MgO(100) buffer layer. Both films were prepared by pulsed
laser deposition (PLD). MgO was grown between 450 and 890 degreesC, and BaT
iO3 was deposited at 1000-1050 degreesC. The films were investigated by mea
ns of X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS)
, ion channeling (RBS/C), transmission electron microscopy and atomic force
microscopy. These techniques revealed that the best epitaxial MgO(100) lay
ers were those grown between 750 and 830 degreesC and at 2 X 10(-3) mbar of
oxygen pressure. The films were characterized by a full width at half maxi
mum of less than 0.5 degrees in the XRD rocking curves (Delta omega) of the
MgO(200) reflection, a minimum RBS/C yield (chi (min)) of similar to5% and
a root-mean-square (rms) roughness of 1.7 nm. The BaTiO3 films grown onto
this buffer layers displayed similar properties: a Delta omega [BaTiO3(200)
] of approximately 0.7 degrees, a chi (min) of 4-5%, and a rms roughness of
approximately 1.0 nm for a film of 440-nm thickness. The epitaxial relatio
nship was found to be [BaTiO3(100)//MgO(100)] similar to //Al2O3(1102). (C)
2001 Elsevier Science B.V. All rights reserved.