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Structural, electrical, and optical properties of polycrystalline NbO 2 thin films grown on glass substrates by solid phase crystallization
Author(s) -
Nakao Shoichiro,
Kamisaka Hideyuki,
Hirose Yasushi,
Hasegawa Tetsuya
Publication year - 2017
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201600604
Subject(s) - materials science , crystallinity , natural bond orbital , crystallite , crystallization , thin film , amorphous solid , electrical resistivity and conductivity , band gap , analytical chemistry (journal) , annealing (glass) , chemical engineering , mineralogy , crystallography , nanotechnology , chemistry , composite material , optoelectronics , metallurgy , density functional theory , organic chemistry , electrical engineering , engineering , computational chemistry
We investigated the structural, electrical, and optical properties of polycrystalline NbO 2 thin films on glass substrates. The NbO 2 films were crystallized from amorphous precursor films grown by pulsed laser deposition at various oxygen partial pressures ( P O2 ). The electrical and optical properties of the precursor films systematically changed with P O2 , demonstrating that the oxygen content of the precursor films can be finely controlled with P O2 . The precursors were crystallized into polycrystalline NbO 2 films by annealing under vacuum at 600 °C. The NbO 2 films possessed extremely flat surfaces with branching patterns. Even optimized films showed a low resistivity ( ρ ) of 2 × 10 2 Ω cm, which is much lower than the bulk value of 1 × 10 4 Ω cm, probably because of the inferior crystallinity of the films compared with that of a bulk NbO 2 crystal. Both oxygen‐rich and ‐poor NbO 2 films showed lower ρ than that of the stoichiometric film. The NbO 2 film with the highest ρ showed an indirect bandgap of 0.7 eV.