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Title: Epitaxial strain and its relaxation at the LaAlO 3/SrTiO 3 interface

A series of LaAlO 3 thin films with different thicknesses were deposited by pulsed laser deposition at temperatures from 720°C to 800°C. The results from grazing incidence x-ray diffraction and reciprocal space mapping indicate that a thin layer of LaAlO 3 adjacent to the SrTiO 3 substrate remains almost coherently strained to the substrate, while the top layer starts to relax quickly above a certain critical thickness, followed by a gradual relaxation at larger film thickness when they are grown at lower temperatures. The atomic force microscopy results show that the fast relaxation is accompanied by the formation of cracks on the film surface. This can be ascribed to the larger energy release rate when compared with the resistance of LaAlO 3 to cracking, according to calculations from the Griffith fracture theory. For films grown at 720°C, a drop in sheet resistance by two orders of magnitude is observed when the top layer starts to relax, indicating a relationship between the strain and the conductivity of the two-dimensional electron gas at the LaAlO 3/SrTiO 3 interface. The strain engineered by growth temperature thus provides a useful tool for the manipulation of the electronic properties of oxide heterointerfaces.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [5] ;  [2]
  1. Temple Univ., Philadelphia, PA (United States). Dept. of Physics; Suzhou Univ. of Science and Technology, Suzhou (China). Research Center for Solid State Physics and Materials and School of Mathematics and Physics
  2. Temple Univ., Philadelphia, PA (United States). Dept. of Physics
  3. Pennsylvania State Univ., University Park, PA (United States). Dept. of Material Sciences and Engineering; Xi'an Jiaotong Univ., Xi'an (China). State Key Lab. for Strength and Vibration of Mechanical Structures and School of Aerospace
  4. Pennsylvania State Univ., University Park, PA (United States). Dept. of Material Sciences and Engineering
  5. Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
SC0004764; DMR-1410714; CMMI-1031403; N00014-1101-0296; 11304089
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 120; Journal Issue: 8; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Temple Univ., Philadelphia, PA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR); National Natural Science Foundation of China (NNSFC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; atomic force microscopy; lattice constants; thin film growth; cracks; reflection high energy electron diffraction; stress relaxation; epitaxy; electron gas
OSTI Identifier:
1467869
Alternate Identifier(s):
OSTI ID: 1328639