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Real-time measurement of oxidation dynamics of sub-stoichiometric tungsten oxide films by pulsed laser deposition

Ranjbar, M ; Sharif University of Technology | 2008

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  1. Type of Document: Article
  2. DOI: 10.1007/s00339-008-4593-0
  3. Publisher: 2008
  4. Abstract:
  5. In this study WO x films were deposited by laser ablation of ultra-pure (5N) tungsten trioxide targets onto SiO2 or silicon substrates at 250°C temperature, 100 mTorr oxygen partial pressure and 1×10-5 Torr vacuum. Surface chemical states and compositions of the deposits were determined by X-ray photoelectron spectroscopy. The results showed that deposits in oxygen partial pressure contain W6+ with x ∼ 3.1, while vacuum-deposited films have different W states with various percentage distributions as W4+>W5+>W 6+>W0, and x ∼ 1. We used fast electrical resistance measurement as a probe to study the deposition process. Film resistance as a function of deposition time in vacuum revealed some microsecond fluctuations modulated on the time variation curve of electrical resistance. We attribute these data to surface absorption and desorption of oxygen during layer deposition. Finally, the effect of the laser beam on the target's structure, surface morphology and chemical state was studied. Our results revealed that in spite of structural variation by laser irradiation, the O/W ratio remained about 3
  6. Keywords:
  7. Oxides ; Pulsed laser applications ; Pulsed laser deposition ; Time measurement ; Tungsten ; Tungsten compounds ; Oxidation dynamics ; Pulsed lasers ; Real-time measurements ; Tungsten oxide films ; Oxide films
  8. Source: Applied Physics A: Materials Science and Processing ; Volume 92, Issue 3 , 7 June , 2008 , Pages 627-634 ; 09478396 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s00339-008-4593-0