R. Thielsch et al., STRUCTURE-RELATED OPTICAL-PROPERTIES OF LASER-DEPOSITED BAXSR1-XTIO3 THIN-FILMS GROWN ON MGO(001) SUBSTRATES, Thin solid films, 301(1-2), 1997, pp. 203-210
Thin films of BaxSr1-xTiO3 (BST), with 0 less than or equal to x less
than or equal to 1, were grown on MgO (001) substrates by off-axis las
er deposition at elevated substrate temperatures. The influence of the
growth temperature and the film composition on the crystalline and mo
rphological properties (film structure, grain size and shape, surface
roughness), as well as on the refractive index n (lambda = 550 nm) and
the optical band gap energy, were studied by X-ray diffraction (XRD),
atomic force microscopy (AFM), scanning electron microscopy (SEM) and
UV-vis spectral reflectometry. The dispersion of the refractive index
was analyzed in terms of the parameters E-o and E-d of the single osc
illator dispersion model of Wemple and DiDomenico. The films with x <
1 show epitaxial growth of close-packed columnar grains with smooth su
rfaces and near-bulk optical properties, whereas the packing density o
f pure BaTiO3 films seems to be reduced and the surface roughness is i
ncreased. A relative decrease in the sticking coefficient of the ad-mo
lecules in the temperature range 730-840 degrees C was found for Ba0.6
5Sr0.35TiO3.