@article{33377,
  keywords = {thin films, Perovskite, lattice constants, substrates, oxide films, quality control, lanthanum compounds, Epitaxial growth, Single crystals, Degrees of freedom (mechanics), Strontium titanates, Heterojunctions, Aluminum compounds, Transition metal oxides, Interfaces (materials), Condensed matter physics, Gallium compounds, Metal testing, Neodymium compounds, Rare earths, Surface treatment, Tantalum compounds, Tensile strain, Transition metals, Atomic flatness, Atomically flat surface, Chemical homogeneity, High quality epitaxial thin films, Layer-by-layer fabrication, Semiconductor electronics, Single crystal substrates, Technological applications},
  author = {A Biswas and C.-H Yang and Ramamoorthy Ramesh and Y.H Jeong},
  title = {Atomically flat single terminated oxide substrate surfaces},
  abstract = {Scientific interest in atomically controlled layer-by-layer fabrication of transition metal oxide thin films and heterostructures has increased intensely in recent decades for basic physics reasons as well as for technological applications. This trend has to do, in part, with the coming post-Moore era, and functional oxide electronics could be regarded as a viable alternative for the current semiconductor electronics. Furthermore, the interface of transition metal oxides is exposing many new emergent phenomena and is increasingly becoming a playground for testing new ideas in condensed matter physics. To achieve high quality epitaxial thin films and heterostructures of transition metal oxides with atomically controlled interfaces, one critical requirement is the use of atomically flat single terminated oxide substrates since the atomic arrangements and the reaction chemistry of the topmost surface layer of substrates determine the growth and consequent properties of the overlying films. Achieving the atomically flat and chemically single terminated surface state of commercially available substrates, however, requires judicious efforts because the surface of as-received substrates is of chemically mixed nature and also often polar. In this review, we summarize the surface treatment procedures to accomplish atomically flat surfaces with single terminating layer for various metal oxide substrates. We particularly focus on the substrates with lattice constant ranging from 4.00 Å to 3.70 Å, as the lattice constant of most perovskite materials falls into this range. For materials outside the range, one can utilize the substrates to induce compressive or tensile strain on the films and explore new states not available in bulk. The substrates covered in this review, which have been chosen with commercial availability and, most importantly, experimental practicality as a criterion, are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3, La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), NdGaO3, LaAlO3, SrLaAlO4, and YAlO3. Analyzing all the established procedures, we conclude that atomically flat surfaces with selective A- or B-site single termination would be obtained for most commercially available oxide substrates. We further note that this topmost surface layer selectivity would provide an additional degree of freedom in searching for unforeseen emergent phenomena and functional applications in epitaxial oxide thin films and heterostructures with atomically controlled interfaces. © 2017},
  year = {2017},
  journal = {Progress in Surface Science},
  volume = {92},
  number = {2},
  pages = {117-141},
  publisher = {Elsevier Ltd},
  issn = {00796816},
  doi = {10.1016/j.progsurf.2017.05.001},
  note = {cited By 20},
  language = {eng},
}