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Title: Direct correlation and strong reduction of native point defects and microwave dielectric loss in air-annealed (Ba,Sr)TiO{sub 3}

We report on the native defect and microwave properties of 1 μm thick Ba{sub 0.50}Sr{sub 0.50}TiO{sub 3} (BST) films grown on MgO (100) substrates by molecular beam epitaxy (MBE). Depth-resolved cathodoluminescence spectroscopy (DRCLS) showed high densities of native point defects in as-deposited BST films, causing strong subgap emission between 2.0 eV and 3.0 eV due to mixed cation V{sub C} and oxygen Vo vacancies. Post growth air anneals reduce these defects with 2.2, 2.65, and 3.0 eV V{sub O} and 2.4 eV V{sub C} intensities decreasing with increasing anneal temperature and by nearly two orders of magnitude after 950 °C annealing. These low-defect annealed BST films exhibited high quality microwave properties, including room temperature interdigitated capacitor tunability of 13% under an electric bias of 40 V and tan δ of 0.002 at 10 GHz and 40 V bias. The results provide a feasible route to grow high quality BST films by MBE through post-air annealing guided by DRCLS.
Authors:
 [1] ; ;  [2] ;  [3] ;  [1] ;  [4]
  1. Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)
  2. Naval Research Laboratory, Washington, DC 20375 (United States)
  3. Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
22399010
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; BARIUM COMPOUNDS; CATHODOLUMINESCENCE; CATIONS; CORRELATIONS; DIELECTRIC MATERIALS; EMISSION SPECTROSCOPY; FILMS; GHZ RANGE; MAGNESIUM OXIDES; MICROWAVE RADIATION; MOLECULAR BEAM EPITAXY; STRONTIUM TITANATES; SUBSTRATES; VACANCIES