Direct evidence for the coexistence of nanoscale high-conduction and low-conduction phases in VO2 films

A systematic investigation of the nanoscale conduction behavior of vanadium dioxide (VO2) films deposited on aluminum oxide (Al2O3) substrates, using conductive atomic force microscopy, is presented. Aside from the macroscale resistance-temperature characteristics, which show a steep insulator-metal...

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Veröffentlicht in:Applied physics letters 2018-10, Vol.113 (17)
Hauptverfasser: Feng, Jiajun, Yang, Cheng, Zhang, Aihua, Li, Qiang, Fan, Zhen, Qin, Minghui, Zeng, Min, Gao, Xingsen, Lin, Yuan, Zhou, Guofu, Lu, Xubing, Liu, J.-M.
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Sprache:eng
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Zusammenfassung:A systematic investigation of the nanoscale conduction behavior of vanadium dioxide (VO2) films deposited on aluminum oxide (Al2O3) substrates, using conductive atomic force microscopy, is presented. Aside from the macroscale resistance-temperature characteristics, which show a steep insulator-metal transition at the transition point Tm ∼ 68 °C, our experiments demonstrate a coexistence of nanoscale high-conduction and low-conduction phases over a broad temperature window (50 K range) across the Tm. In addition, the area (volume) fraction of the high-conduction phase increases with increasing temperature across the transition point. The current-voltage data obtained on a nanoscale indicate that the high-conduction phase is not a good metal. When the temperature increased across the Tm, the probed charge transport behavior of the high-conduction phase is found to change from a mechanism dominated by space-charge limited current to a mechanism dominated by Schottky emission.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5032270