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Du JL, Fang Y, Fu EG, Ding X, Yu KY, Wang YG, Wang YQ, Baldwin JK, Wang PP, Bai Q. What determines the interfacial configuration of Nb/Al 2O 3 and Nb/MgO interface. Sci Rep 2016; 6:33931. [PMID: 27698458 PMCID: PMC5048433 DOI: 10.1038/srep33931] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 08/25/2016] [Indexed: 12/02/2022] Open
Abstract
Nb films are deposited on single crystal Al2O3 (110) and MgO(111) substrates by e-beam evaporation technique. Structure of Nb films and orientation relationships (ORs) of Nb/Al2O3 and Nb/MgO interface are studied and compared by the combination of experiments and simulations. The experiments show that the Nb films obtain strong (110) texture, and the Nb film on Al2O3(110) substrate shows a higher crystalline quality than that on MgO(111) substrate. First principle calculations show that both the lattice mismatch and the strength of interface bonding play major roles in determining the crystalline perfection of Nb films and ORs between Nb films and single crystal ceramic substrates. The fundamental mechanisms for forming the interfacial configuration in terms of the lattice mismatch and the strength of interface bonding are discussed.
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Affiliation(s)
- J L Du
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Y Fang
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - E G Fu
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, P. R. China
| | - X Ding
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China
| | - K Y Yu
- Department of Materials Science and Engineering, China University of Petroleum, Beijing 102249, P. R. China
| | - Y G Wang
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Y Q Wang
- Experimental Physical Sciences Directorate, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - J K Baldwin
- Experimental Physical Sciences Directorate, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - P P Wang
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Q Bai
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, P. R. China
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Kaspar TC, Chamberlin SE, Bowden ME, Colby R, Shutthanandan V, Manandhar S, Wang Y, Sushko PV, Chambers SA. Impact of lattice mismatch and stoichiometry on the structure and bandgap of (Fe,Cr)2O3 epitaxial thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:135005. [PMID: 24625641 DOI: 10.1088/0953-8984/26/13/135005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The structural properties of phase-pure epitaxial (Fe1-xCrx)2O3 thin films deposited on α-Al2O3(0 0 0 1) substrates by oxygen-plasma-assisted molecular beam epitaxy are investigated across the composition range using x-ray photoelectron spectroscopy, high-resolution x-ray diffraction, scanning transmission electron microscopy and electron energy loss spectroscopy, and non-Rutherford resonant elastic scattering measurements. The films possess a columnar grain structure with uniform mixing of cations on the nanometer scale. Fe-rich films are relaxed and appear to be slightly oxygen-rich, while Cr-rich films remain partially strained to the Al2O3 substrate and are found to be oxygen deficient. A model is proposed to explain the oxygen stoichiometry results based on the energetics of oxygen defect formation and rate of oxygen diffusion in the corundum lattice, and the dependence on the cation composition. Deliberately introducing residual compressive biaxial strain into (Fe1-xCrx)2O3 thin films (x = 0, 0.41, 0.52) by employing a Cr2O3 buffer layer is shown to narrow the optical bandgap, from 1.80(1) eV for relaxed (Fe0.47Cr0.53)2O3 to 1.77(1) eV for partially strained (Fe0.48Cr0.52)2O3. The relationships which are elucidated between epitaxial film structure and optical properties can be applied to bandgap optimization in the (Fe,Cr)2O3 system.
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Affiliation(s)
- T C Kaspar
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA
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