Microstructure of BaxSr1−xTiO3 thin films grown on sapphire substrates

Soft-mode spectroscopy of BaTiO3 thin films

“…Most probably, it is connected with the strong influence of the substrate on the 1 1 1 -ordered structure of the BTO1 film. 13 It is important to underline that the obtained spectra of dielectric function are effective and together with intrinsic properties they may include geometric factors specific for a composite system built-up of variously oriented anisotropic particles. We have not introduced any geometrical parameter describing these effects into our model to escape possible ambiguities with non-regularity and grain-anisotropy of the thinfilm structure.…”

“…In-plane compressive strain was assigned to the difference in thermal expansion coefficient of BaTiO 3 and sapphire. 13 AFM indicated no clear granularity on the BTO1 surface, but well resolved grains on the BTO2 and BTO3 surfaces. Far-infrared (FIR) transmittance measurements in the 20-300 cm −1 frequency range (limited at high frequencies by the substrate transparency) and 10-520 K temperature interval, carried out using Bruker IFS 113v Fourier transform interferometer, were complemented by time-domain transmission terahertz spectroscopy (TDTTS) in the 8-50 cm −1 range 15 at room temperature.…”

Structural and dielectric properties of epitaxial (Ba,Sr)TiO3 films on c-Al2O3 with ultra-thin TiN sacrificial template

“…Nevertheless, since the epitaxial growth of BST without any buffer layers has also been reported, 15 24) and the Ti configuration in BST (hhh) plane is a subset of that in TiN (hhh) plane. Therefore, even an ultra-thin TiN layer would be enough to promote the epitaxial growth of BST on c-Al 2 O 3 with (111)-orientation.…”

“…Sapphire (Al 2 O 3 ) is one of few possible single crystal wafers. Although it has a large lattice mismatch with BST, some of the reported BST films show the epitaxial growth on c-Al 2 O 3 [i.e., (0001) Al 2 O 3 ] using metalorganic chemical vapor deposition 15) and sputtering. 16) On the other hand, polycrystalline films have been also often reported, 17), 18) which implies the importance of the growth control for such an unmatched interface.…”

Enhanced tunability of magnetron sputtered Ba0.5Sr0.5TiO3 thin films on c-plane sapphire substrates

“…Highly ͑111͒ oriented films have previously been observed in Ba 0.1 Sr 0.9 TiO 3 films grown by metal-organic chemical vapor deposition ͑MOCVD͒ on c-plane sapphire substrates. 11 BST ͑111͒ scans revealed a full width at half maximum ͑FWHM͒ of ϳ7.7°for the as-deposited film. After postdeposition annealing, the FWHM reduced to ϳ4.9°.…”