Doped Vanadium Dioxide with Enhanced Infrared Modulation

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Authors
  1. Paradis, S.
  2. Laou, P.
  3. Alain, D.
Corporate Authors
Defence R&D Canada - Valcartier, Valcartier QUE (CAN)
Abstract
The purpose of this memorandum is to investigate the effect of selected dopants (namely tungsten (W) and W-titanium (Ti)) on semiconducting to metallic phase transition of the vanadium dioxide (VO2) in the longwave infrared (LWIR) range. The specific properties investigated in this study are the transition temperature Tt, the electrical resistivity and the optical transmittance. The fabrication of films was done by magnetron radio-frequency sputtering technique. The results indicated that Tt of our undoped VO2 films is ~ 65°C and can be brought down to ~ 15°C with ~2.1 at.% of W doping. When the film is in the metallic phase (above the Tt), the electrical resistivity of undoped films drops three orders of magnitude while it drops two orders of magnitude in W-doped films with an electrical hysteresis of less than 10°C in both cases. Co-doping with W (~1 at.%) and Ti (of ~6 at.%) greatly modifies the resistivity slope, the latter showing no abrupt transition but rather a smooth, linear transition over a large temperature range with Tt near 55°C. The resistivity drop upon heating of the co-doped film is less than one order of magnitude but its electrical hysteresis is totally suppressed. Regarding optical transmittance, all films under investigation have high transmission (>75%) at room temperature (RT) in the IR region. In the metallic phase (above Tt), undoped films become nearly opaque with a tra

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Report Number
DRDC-VALCARTIER-TM-2007-002 — Technical Memorandum
Date of publication
01 Sep 2007
Number of Pages
36
DSTKIM No
CA029782
CANDIS No
528222
Format(s):
CD ROM

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