The metal–insulator transition (MIT) in vanadium dioxide (VO2) thin films is strongly affected by grain size, thickness, and interfacial properties. Typically, a minimum thickness around 50 nm is required for VO2 to exhibit a significant MIT when functional substrates like sapphire and silicon are used. Several works have shown that thin films below 20 nm, with up to 2–3 decades of change in the resistance across the MIT, can be achieved but require complex pre- or postprocessing of the samples. We show that predeposition substrate condition control facilitates the direct growth of VO2 ultrathin 15 nm films, exhibiting a resistance change between 3 and 4 decades across the MIT. Our findings indicate that the interface between the film and the substrate is crucial in determining the initial growth layers and the structural evolution. With appropriate substrate surface treatment, the desired VO2 MIT can be enhanced regardless of the substrate crystallographic orientation. Moreover, we propose a novel approach to obtain large resistance changes across the MIT in ultrathin VO2 films by incorporating a predeposited 1.5 nm vanadium oxide buffer layer, thereby eliminating the need to use different materials or complex pre- or postprocessing of the samples. Here we also demonstrate that this method improves the transition of 25–50 nm VO2 thin films on silicon substrates. Our study reveals a simple approach for direct growth of ultrathin VO2 films exhibiting a significant MIT, which is commonly accepted unattainable over substrates of technological importance, such as sapphire and silicon.
Hofer, Juan Andres, et al. "Ultrathin VO<sub>2</sub> Films on Functional Substrates." ACS Applied Materials and Interfaces, vol. 17, no. 15, Apr. 2025. https://doi.org/10.1021/acsami.5c02682
Hofer, Juan Andres, Basaran, Ali C., Pofelski, Alexandre, Wang, Tianxing Damir, Palin, Victor, Zhu, Yimei, & Schuller, Ivan K. (2025). Ultrathin VO<sub>2</sub> Films on Functional Substrates. ACS Applied Materials and Interfaces, 17(15). https://doi.org/10.1021/acsami.5c02682
Hofer, Juan Andres, Basaran, Ali C., Pofelski, Alexandre, et al., "Ultrathin VO<sub>2</sub> Films on Functional Substrates," ACS Applied Materials and Interfaces 17, no. 15 (2025), https://doi.org/10.1021/acsami.5c02682
@article{osti_2568096,
author = {Hofer, Juan Andres and Basaran, Ali C. and Pofelski, Alexandre and Wang, Tianxing Damir and Palin, Victor and Zhu, Yimei and Schuller, Ivan K.},
title = {Ultrathin VO<sub>2</sub> Films on Functional Substrates},
annote = {The metal–insulator transition (MIT) in vanadium dioxide (VO2) thin films is strongly affected by grain size, thickness, and interfacial properties. Typically, a minimum thickness around 50 nm is required for VO2 to exhibit a significant MIT when functional substrates like sapphire and silicon are used. Several works have shown that thin films below 20 nm, with up to 2–3 decades of change in the resistance across the MIT, can be achieved but require complex pre- or postprocessing of the samples. We show that predeposition substrate condition control facilitates the direct growth of VO2 ultrathin 15 nm films, exhibiting a resistance change between 3 and 4 decades across the MIT. Our findings indicate that the interface between the film and the substrate is crucial in determining the initial growth layers and the structural evolution. With appropriate substrate surface treatment, the desired VO2 MIT can be enhanced regardless of the substrate crystallographic orientation. Moreover, we propose a novel approach to obtain large resistance changes across the MIT in ultrathin VO2 films by incorporating a predeposited 1.5 nm vanadium oxide buffer layer, thereby eliminating the need to use different materials or complex pre- or postprocessing of the samples. Here we also demonstrate that this method improves the transition of 25–50 nm VO2 thin films on silicon substrates. Our study reveals a simple approach for direct growth of ultrathin VO2 films exhibiting a significant MIT, which is commonly accepted unattainable over substrates of technological importance, such as sapphire and silicon.},
doi = {10.1021/acsami.5c02682},
url = {https://www.osti.gov/biblio/2568096},
journal = {ACS Applied Materials and Interfaces},
issn = {ISSN 1944-8252},
number = {15},
volume = {17},
place = {United States},
publisher = {American Chemical Society (ACS)},
year = {2025},
month = {04}}
Brookhaven National Laboratory (BNL), Upton, NY (United States); Energy Frontier Research Centers (EFRC) (United States). Quantum Materials for Energy Efficient Neuromorphic Computing (Q-MEEN-C)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, Vol. 356, Issue 1735https://doi.org/10.1098/rsta.1998.0146