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Title: Characteristics of LaB{sub 6} thin films grown by pulsed laser deposition

Journal Article · · Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
DOI:https://doi.org/10.1116/1.4960647· OSTI ID:22592845
; ;  [1];  [2];  [3];  [4];  [5]; ;  [6]
  1. National Institute for Lasers, Plasma, and Radiation Physics, Magurele 077125 (Romania)
  2. Materials Science Department, Transilvania University of Brasov, Brasov 500036 (Romania)
  3. Major Analytical Instrumentation Center (MAIC), University of Florida, Gainesville, Florida 32611 (United States)
  4. Faculty of Applied Chemistry and Material Science, Department of Science and Engineering of Oxide Materials and Nanomaterials, University Politehnica of Bucharest, Bucharest 011061, 060042 (Romania)
  5. Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, Ohio 45433-7707 (United States)
  6. Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXA) Wright-Patterson AFB, Ohio 45433-7707 and Energy and Environmental Engineering Division, University of Dayton Research Institute, Dayton, Ohio 45469-0170 (United States)

LaB{sub 6} thin films were deposited at a temperature of 500 °C under vacuum or Ar atmosphere by the pulsed laser deposition technique on (100) Si substrates using a KrF laser. Grazing incidence x-ray diffraction investigations found that films were nanocrystalline, with grain size dimensions from 86 to 102 nm and exhibited microstrain values around 1.1%. Simulations of the x-ray reflectivity curves acquired from the deposited films showed that films had a density around 4.55 g/cm{sup 3}, and were very smooth, with a surface roughness root-mean-square of 1.5 nm, which was also confirmed by scanning electron and atomic force microscopy measurements. All films were covered by a ∼2 nm thick contamination layer that formed when samples were exposed to the ambient. Auger electron spectroscopy investigations found very low oxygen impurity levels below 1.5 at. % once the contamination surface layer was removed by Ar ion sputtering. Four point probe measurements showed that films were conductive, with a resistivity value around 200 μΩ cm for those deposited under Ar atmosphere and slightly higher for those deposited under vacuum. Nanoindentation and scratch investigations showed that films were rather hard, H ∼ 16 GPa, E ∼ 165 GPa, and adherent to the substrate. Thermionic emission measurements indicated a work function value of 2.66 eV, very similar to other reported values for LaB{sub 6}.

OSTI ID:
22592845
Journal Information:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 34, Issue 5; Other Information: (c) 2016 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
Country of Publication:
United States
Language:
English