Domain structure and surface morphology of epitaxial PbTiO3/SrRuO3 heterostructures on vicinal (001) SrTiO3 substrates

Epitaxial ferroelectric PbTiO3/SrRuO3 heterostructures have been grown on (001) SrTiO3 substrates with 1.7 and 5° miscut toward [010] by rf magnetron sputtering. X-ray diffraction indicates that heterostructures with thin PbTiO3 layer (120, 400, and 1250 Å) consist of purely c-axis PbTiO3 domain, while the thicker PbTiO3 layer (2500 Å) contains both a-axis and c-axis PbTiO3 domains. The bottom SrRuO3 layer is single domain with [110] normal orientation. Furthermore, both PbTiO3 and SrRuO3 layers are of very good crystalline quality from the measurements of the full width at half maximum of rocking curve and in-plane φ scans. Atomic force microscopy studies show that both SrRuO3 and PbTiO3 layers are grown by step flow mechanism, which results in very smooth surfaces (the root mean square roughness ≈12 Å for a 400 Å PbTiO3/SrRuO3 heterostructure on a 1.7° miscut substrate over a 2×2 μm area). Our results demonstrate that the high quality epitaxial ferroelectric PbTiO3 heterostructures can be prepared by using SrRuO3 bottom electrodes on miscut (001) SrTiO3 substrates for ferroelectric device applications.