Well-Ordered Self-Assembly Growth of Strain-Modulated SrTiO3 Thin Films: Templates for Complex Oxide Quantum Wires
Well-ordered self-assembled SrTiO3 thin film, as a template for complex oxide quantum wires, was fabricated on LaAlO3 (100) single crystal substrates with laser molecular beam epitaxy. The self-assembled growth was in-situ monitored by reflective high energy electron diffraction. The morphology evolutions of the films as a function of thickness were studied by ex-situ atomic force microscopy. As the thickness of the films increased from 3.875nm to 46.5nm gradually, the compressive stress-induced SrTiO3 films exhibited a periodic well-ordered ripple structure, which formed a unique nanoassembled template for the fabrication of quantum wires. Small angle X-ray scattering technique was employed to investigate the structure. Symmetric satellite peaks were discovered, indicating the well-ordered superstructure. In contrast, the similar superstructure was not observed during the growth of the tensile stress-induced LaAlO3 films on SrTiO3 substrates. The Compressive stress was considered as the main reason of the self-assembled growth, and systematical elucidation about strain mechanism was discussed. These results might provide an efficient method for the controllable formation of well-aligned template of quantum wire for complex oxide with desirable structure via proper modulation of strains.
Z.Y. Zhong, H. Saka, T.H. Kim, E.A. Holm, Y.F. Han and X.S. Xie
Y. R. Li et al., "Well-Ordered Self-Assembly Growth of Strain-Modulated SrTiO3 Thin Films: Templates for Complex Oxide Quantum Wires", Materials Science Forum, Vols. 475-479, pp. 4255-4260, 2005