Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO3 heteroepitaxy

Abstract

Heteroepitaxial ZnO and SrRuO3 were grown on SrTiO3 (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO3 pillars was observed, with the growth direction changing from [111]SRO to [011]SRO as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO3 substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO3 and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices.

Metal Oxide Nanocomposites: A Perspective from Strain, Defect, and Interface

“…The strain in VANs could be controlled by vertical interface rather than lateral interface in heterostructures. Such effect changed the orientation of SrRuO 3 phase from [110] to [011] in SrRuO 3 :ZnO/STO (111) VANs by increasing the film thickness . The vertical strain stems from the elastic coupling of the vertical interfaces between the two phases.…”

Nanoscale structural investigation of Zn1–x Mg x O alloy films on polar and nonpolar ZnO substrates with different Mg contents*

“…[13,14] For example, novel optoelectronics and memory devices have been fabricated by combining SrTiO 3 , [15] which exhibits an abundance of physical properties, such as two-dimensional (2D) electron gas, [16] ferroelectricity, [17] magnetism, [18] and superconductivity. [19] Similarly, integrating perovskite Pb(Zr,Ti)O 3 , [20] SrRuO 3 , [21] and BiFeO 3 [22] with wurtzite ZnO promotes faster response time and the production of more efficient field-effect transistors or resistance random access memory devices. In thermal equilibrium, ZnO is hexagonal wurtzite, while the crystal structure of MgO is cubic rock salt.…”

Atomic Structure and Chemistry of Self‐Assembled Nanopillar Composite Oxides

“…Therefore, the investigations on the nanoscale structures and their interfaces, chemistry, and electronic structures are crucial for not only revealing the mechanism of nanocomposite formation but also understanding the underlying structure–property relation, which consequently will guide us the control of nanocomposite growth and as a result the functionality engineering for device applications. However, the buried interfaces in nanocomposites are usually diffuse, rough, and/or heterogeneous, making it very difficult to extract the atomic bonding information and chemistry of interfaces.…”