We present the first-time growth of bulk
BaSnO3 single crystals from the melt by direct solidification, their basic
electrical and optical properties as well as their structural quality. Our measurement
of the melting point (MP) of BaSnO3 amounts to 1855 °C ± 25 K. At this
temperature an intensive decomposition and non-stoichiometric evaporation takes
place as the partial pressure of SnO(g) is about 90 times higher than that of
BaO(g). X ray powder diffraction identified only the BaSnO3 perovskite phase,
while narrow rocking curves having a full width at half maximum of 26 arcsec
and etch pit densities below 106 cm−2 confirm a high degree of structural
perfection of the single crystals. In this respect they surpass the structural
properties of those single crystals that were reported in the literature. The
electrical conductivity of nominally undoped crystals depends on the growth
conditions and ranges from insulating to medium n-type conductivity. After
post-growth annealing in an oxidizing atmosphere undoped crystals are generally
insulating. Doping the crystals with lanthanum during growth results in a high
n-type conductivity. For a La doping concentration of 0.123 wt.% we measured an
electron concentration of 3.3 × 1019 cm−3 and an electron mobility of 219 cm2
V−1 s−1. Based on optical absorption measurements we determined an energy of
3.17 ± 0.04 eV at 5 K and of 2.99 ± 0.04 eV at 297 K for the indirect band
gap of BaSnO3.
Source:IOPscience
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