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Title: Thermochromic VO{sub 2} nanorods made by sputter deposition: Growth conditions and optical modeling

Reactive dc magnetron sputtering onto glass-based substrates yielded deposits of thermochromic VO{sub 2} with well-developed nanorods and nanowires. Their formation was promoted by high substrate temperature (above {approx}500 Degree-Sign C), sufficient film thickness, proper inlet of the reactive gas, dispersed gold 'seeds,' and pronounced substrate roughness. Rutherford back scattering ascertained mass thicknesses, scanning electron microscopy depicted the nanostructures, and glancing incidence X-ray diffraction proved that single-phase VO{sub 2} was normally formed. Spectrophotometric measurements of total and diffuse transmittance and reflectance on VO{sub 2} thin films, at room temperature and {approx}100 Degree-Sign C, allowed us to determine complex dielectric functions below and above the 'critical' temperature for thermochromic switching ({approx}68 Degree-Sign C). These data were then used in computations based on the Bruggeman effective medium theory applied to randomly oriented prolate spheroidal structural units to derive the optical properties of the deposits. Experimental and computed data on spectral absorptance were found to be in good qualitative agreement.
Authors:
; ;  [1] ; ;  [2]
  1. Department of Engineering Sciences, Angstroem Laboratory, Uppsala University, P.O. Box 534, SE-75121 Uppsala (Sweden)
  2. Department of Micro Engineering, Kyoto University-Katsura, C3 b4N01, Kyoto 615-8540 (Japan)
Publication Date:
OSTI Identifier:
22122838
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 3; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; BACKSCATTERING; DEPOSITION; DEPOSITS; DIELECTRIC MATERIALS; GLASS; MAGNETRONS; MASS; OPTICAL PROPERTIES; QUANTUM WIRES; RANDOMNESS; ROUGHNESS; RUTHERFORD BACKSCATTERING SPECTROSCOPY; SCANNING ELECTRON MICROSCOPY; SPECTROPHOTOMETRY; SPUTTERING; SUBSTRATES; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; VANADIUM OXIDES; X-RAY DIFFRACTION