Growth of BiFeO3/SrTiO3 artificial superlattice structure by RF sputtering

• Published in: Journal of crystal growth 2011-11, Vol.334 (1), p.90-95
• Main Authors: Chiu, Shang-Jui, Liu, Yen-Ting, Lee, Hsin-Yi, Yu, Ge-Ping, Huang, Jia-Hong
• Format: Article
• Language: English
• Subjects: A1. X-ray diffraction; A3. RF sputtering; A3. Thin film/epitaxial growth; B2. Ferroelectric materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2011.08.019

Asymmetric superlattice structures consisting of multiferroic BiFeO3 (BFO) and paraelectric SrTiO3 (STO) sublayers were grown on a Nb-doped STO substrate by RF magnetron sputtering at temperatures in the range 500–800°C. For substrate temperatures less than 500°C and at 800°C, only poorly crystalline films resulted, whereas a BFO/STO superlattice structure film of great crystalline quality was obtained for a substrate temperature in the range 550–750°C. The formation of a superlattice structure was confirmed through both the appearance of Bragg lines separated by Kiessig fringes in X-ray reflectivity curves and the satellite features of a (002) diffraction pattern. The clearly discernible main and satellite features on both sides of the substrate about the (002) STO Bragg peak of superlattice films indicate the high quality of the BFO/STO artificial superlattice structure. For BFO/STO superlattice films deposited at 600–700°C, the increased crystalline quality with smaller interface roughness correlates with larger lattice strain and remanent polarization of the film. The lattice strain and interface quality might be important factors that influence the leakage and ferroelectric properties in BFO/STO artificial superlattices. ► BiFeO3/SrTiO3 (BFO/STO) superlattices structure was fabricated with RF sputtering. ► X-ray result shows high quality of BFO/STO superlattices structure. ► Largest remanent polarization (Pr) occurs at deposition temperature 600°C. ► Ferroelectric properties are highly correlated with lattice strain. ► Crystalline and interface quality also affect ferroelectric properties.