Ferroelectricity in nonstoichiometric SrTiO3 films studied by ultraviolet Raman spectroscopy.

Authors :: Tenne, D. A.
Farrar, A. K.
Brooks, C. M.
Heeg, T.
Schubert, J.
Jang, H. W.
Bark, C. W.
Folkman, C. M.
Eom, C. B.
Schlom, D. G.
Source :: Applied Physics Letters; 10/4/2010, Vol. 97 Issue 14, p142901, 3p
Publication Year :: 2010
Abstract: Homoepitaxial Sr<subscript>1+x</subscript>TiO<subscript>3+δ</subscript> films with -0.2≤x≤0.25 grown by reactive molecular-beam epitaxy on SrTiO<subscript>3</subscript> (001) substrates have been studied by ultraviolet Raman spectroscopy. Nonstoichiometry for strontium-deficient compositions leads to the appearance of strong first-order Raman scattering at low temperatures, which decreases with increasing temperature and disappears at about 350 K. This indicates the appearance of a spontaneous polarization with a paraelectric-to-ferroelectric transition temperature above room temperature. Strontium-rich samples also show a strong first-order Raman signal, but the peaks are significantly broader and exhibit a less pronounced temperature dependence, indicating a stronger contribution of the disorder-activated mechanism in Raman scattering. [ABSTRACT FROM AUTHOR]

Subjects :: SEMICONDUCTOR films
FERROELECTRICITY
STRONTIUM compounds
RAMAN spectroscopy
HOMOEPITAXY
MOLECULAR beam epitaxy
RAMAN effect
POLARIZATION (Electricity)

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