X-ray photoelectron spectroscopy and conducting atomic force microscopy investigations on dual ion beam sputtered MgO ultrathin films |
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Authors: | Braj Bhusan SinghVikash Agrawal Amish G. JoshiSujeet Chaudhary |
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Affiliation: | a Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016, Indiab CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110 012, India |
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Abstract: | Ultrathin films of MgO (~ 6 nm) were deposited on Si(100) using dual ion beam sputtering in different partial pressures of oxygen. These thin films were characterized by X-ray photoelectron spectroscopy (XPS) for chemical state analysis and conducting atomic force microscopy for topography and local conductivity map. No trace of metal Mg was evidenced in these MgO films. The XPS analysis clearly brought out the formation of oxygen interstitials and Mg(OH)2 primarily due to the presence of residual water vapors in the chamber. An optimum value of oxygen partial pressure of ~ 4.4 × 10− 2 Pa is identified with regard to homogeneity of film and stoichiometry across the film thickness (O:Mg::0.93-0.97). The local conductivity mapping investigations also established the film homogeneity in respect of electrical resistivity. Non-linear local current-voltage curves revealed typical tunneling characteristics with barrier width of ~ 5.6 nm and barrier height of ~ 0.92 eV. |
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Keywords: | Magnesium oxide Thin films Dual ion beam sputtering X-ray photoelectron spectroscopy Conductive atomic force microscopy |
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