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An Invariable Temperature during the Phase Transition of W Doped VO 2 Film
Author(s) -
Hong SeongCheol,
Lee Myeongsoon,
Kim Don
Publication year - 2020
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.11975
Subject(s) - materials science , electrical resistivity and conductivity , doping , analytical chemistry (journal) , transition temperature , transmittance , phase transition , sapphire , band gap , hysteresis , condensed matter physics , chemistry , optics , superconductivity , optoelectronics , laser , physics , chromatography , electrical engineering , engineering
The phase transition temperature of the functional VO 2 films was adjusted to near room temperature by the W 6+ doping. The V 1− x W x O 2 (0 ≤ x ≤ 0.04) films were deposited by the one‐step thermal decomposition process (30 min at 793 K) on a sapphire (0001) substrate under inert conditions. The electrical resistivity of the films showed that the ending point of the metal to insulator transition ( T CE ) of the pure VO 2 phase transition, which appeared at ~310 K, was shifted down to ~265 K along with the increased doping level of W. The hysteresis gap between cooling and heating cycles in the plot of temperature vs. electrical resistivity for the films decreased from ~25 to ~2 K by the increased W level. The transition temperature shift and the hysteresis gap decrement were also observed in the measurement of infrared (IR) transmittance near the transition temperature. The degree of IR (1550 nm) transmittance of the VO 2 film in the low‐temperature region was decreased from ~80 to ~40% by the W doping, but nearly the same transmittance in the high‐temperature region. Even though the characteristics of the transition in resistivity and transmittance measurements were greatly altered by the W doping, the starting point of the metal to insulator transition ( T CS ) was nearly constant, T CS ~338 K.