Single crystal thin films of conductive oxides SrRuO₃ and ferroelectric heterostructures

Abstract

We have grown epitaxial thin films of the conductive oxide SrRuO₃ with well controlled surface morphology and domain structure using vicinal (001) SrTiO₃ substrates. Scanning tunneling microscopy and x-ray diffraction show that the SrRuO₃ thin films on miscut (001) SrTiO₃ substrates with miscut angle > 2° grow by step flow in one direction leading to single crystal films. In contrast, the SrRuO₃ thin films on exact (001) SrTiO₃ substrates grow by two dimensional nucleation resulting in a two domain in-plane structure. The single crystal thin films have been used as electrodes for the growth of epitaxial ferroelectric PbTiO₃ and PZT layers. The PbTiO₃/SrRuO₃ and PZT/SrRuO₃ heterostructures have high crystalline quality, coherent interfaces and a cube-on-cube epitaxial growth with respect to the substrate. These epitaxial heterostructures have superior fatigue characteristics and look promising for the fabrication of integrated single crystal ferroelectric devices.

Key Words:

• ferroelectric heterostructures
• SrRuO₃
• electrodes
• growth
• domain structures
• perovskite