title: Growth of Highly Strained CeO2Ultrathin Films.
abstract: Large biaxial strain is a promising route to tune the functionalities of oxide thin films. However, large strain is often not fully realized due to the formation of misfit dislocations at the film/substrate interface. In this work, we examine the growth of strained ceria (CeO2) thin films on (001)-oriented single crystal yttria-stabilized zirconia (YSZ) via pulsed-laser deposition. By varying the film thickness systematically between 1 and 430 nm, we demonstrate that ultrathin ceria films are coherently strained to the YSZ substrate for thicknesses up to 2.7 nm, despite the large lattice mismatch (∼5%). The coherency is confirmed by both X-ray diffraction and high-resolution transmission electron microscopy. This thickness is several times greater than the predicted equilibrium critical thickness. Partial strain relaxation is achieved by forming semirelaxed surface islands rather than by directly nucleating dislocations. In situ reflective high-energy electron diffraction during growth confirms the transition from 2-D (layer-by-layer) to 3-D (island) at a film thickness of ∼1 nm, which is further supported by atomic force microscopy. We propose that dislocations likely nucleate near the surface islands and glide to the film/substrate interface, as evidenced by the presence of 60° dislocations. An improved understanding of growing oxide thin films with a large misfit lays the foundation to systematically explore the impact of strain and dislocations on properties such as ionic transport and redox chemistry.
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Yezhou
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Sang Chul
authors.initials: SC
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Matteo
authors.initials: M
authors.lastname: Monti
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Colvin
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Zhuoluo A
authors.initials: ZA
authors.lastname: Feng
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: William D
authors.initials: WD
authors.lastname: Nix
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Toney
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Sinclair
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Applied Physics, Stanford University , Stanford, California 94305, United States.|Stanford Synchrotron Radiation Lightsource and ∥Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: William C
authors.initials: WC
authors.lastname: Chueh
keywords: ceria; dislocation; strain; yttria-stabilized zirconia