Field-induced reversible insulator-to-metal transition and the onset of ferroelectricity in molybdenum trioxide films

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Date
2023-06-01
Authors
Dragoman, Mircea
Modreanu, Mircea
Sheehan, Brendan
Vulpe, Silviu
Romanitan, Cosmin
Aldrigo, Martino
Dinescu, Adrian
Serban, Andreea Bianca
Dragoman, Daniela
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American Institute of Physics
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Abstract
This paper presents the experimental evidence of reversible insulator–metal transition (IMT) in thin-film amorphous molybdenum trioxide (MoO3) induced by electric fields of just a few volts. The presence of oxygen vacancies in MoO3 is considered to play a significant role in the reported reversible IMT. The oxygen vacancies not only impact MoO3 stoichiometry but also the optical bandgap. The subthreshold slope for IMT in 10 nm-thick MoO3-based devices is 48.3 mV/decade, which represents a transition from an insulator to a metallic state, and the electric field threshold for such a transition was found to be equal to 0.034 V/Å. Following the IMT in MoO3, there are six orders of magnitude differences between the resistivity of the insulator state (27.5 M Ω at −9 V) and the metallic state (80 Ω between +5 and +9 V). In addition, we reported stabilization of a nanocrystalline hexagonal MoO3 (h-MoO3) phase in thicker MoO3 (150 nm-thick) in the presence of oxygen vacancies that behave as a wide bandgap (3.1 eV) ferroelectric semiconductor with a coercive field of about 50 kV/cm, a saturation polarization of about 30 μC/cm2, and a remanent polarization of about 10 μC/cm2. This ferroelectricity in nanocrystalline h-MoO3 (150 nm-thick) remains stable even after 8 months of storage of the sample in ambient conditions, with remanent polarization increasing up to 20 μC/cm2. These are unexpected results from MoO3.
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Keywords
Reversible insulator–metal transition (IMT) , Thin-film amorphous molybdenum trioxide (MoO3) , Electric field
Citation
Dragoman, M., Modreanu, M., Sheehan, B., Vulpe, S., Romanitan, C., Aldrigo, M., Dinescu, A., Serban, A. B. and Dragoman, D. (2023) 'Field-induced reversible insulator-to-metal transition and the onset of ferroelectricity in molybdenum trioxide films', Journal of Applied Physics, 133(21), 215101 (11pp). doi: 10.1063/5.0151117
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© 2023, the Authors. Published under an exclusive license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared as: Dragoman, M., Modreanu, M., Sheehan, B., Vulpe, S., Romanitan, C., Aldrigo, M., Dinescu, A., Serban, A. B. and Dragoman, D. (2023) 'Field-induced reversible insulator-to-metal transition and the onset of ferroelectricity in molybdenum trioxide films', Journal of Applied Physics, 133(21), 215101 (11pp), doi: 10.1063/5.0151117, and may be found at: https://doi.org/10.1063/5.0151117