Structural and Ferroelectric Properties of Domain-Structure-Controlled BiFeO3 Thin Films Prepared by Dual-Ion-Beam Sputtering

概要

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BiFeO3 (BFO) thin films have been grown on vicinal SrTiO3 (STO) (001) substrates by dual-ion-beam sputtering. The Bi/Fe composition ratio was optimized by adjusting the beam current ratio of a dual-ion beam. The domain structure was controlled using a vicinal STO substrate along \langle 100\rangle and \langle 110\rangle. From the results of X-ray diffraction analysis and piezoelectric force microscopy, it is found that BFO thin films grown on vicinal STO along \langle 100\rangle and \langle 110\rangle show stripe and single-domain structures, respectively. It is found that the reduction in the length of non-180° domain walls improves leakage current characteristics, resulting in an enhancement of ferroelectric D--E characteristics. The single-domain BFO thin film shows excellent D--E hysteresis loops at room temperature, with a double remanent polarization (2P_{\text{r}}) and a double coercive field (2E_{\text{c}}) of 140 μC/cm2 and 340 kV/cm, respectively.
2012-09-25