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Maher O, Bernini R, Harnack N, Gotsmann B, Sousa M, Bragaglia V, Karg S. Highly reproducible and CMOS-compatible VO 2-based oscillators for brain-inspired computing. Sci Rep 2024; 14:11600. [PMID: 38773144 PMCID: PMC11109144 DOI: 10.1038/s41598-024-61294-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/03/2024] [Indexed: 05/23/2024] Open
Abstract
With remarkable electrical and optical switching properties induced at low power and near room temperature (68 °C), vanadium dioxide (VO2) has sparked rising interest in unconventional computing among the phase-change materials research community. The scalability and the potential to compute beyond the von Neumann model make VO2 especially appealing for implementation in oscillating neural networks for artificial intelligence applications, to solve constraint satisfaction problems, and for pattern recognition. Its integration into large networks of oscillators on a Silicon platform still poses challenges associated with the stabilization in the correct oxidation state and the ability to fabricate a structure with predictable electrical behavior showing very low variability. In this work, the role played by the different annealing parameters applied by three methods (slow thermal annealing, flash annealing, and rapid thermal annealing), following the vanadium oxide atomic layer deposition, on the formation of VO2 grains is studied and an optimal substrate stack configuration that minimizes variability between devices is proposed. Material and electrical characterizations are performed on the different films and a step-by-step recipe to build reproducible VO2-based oscillators is presented, which is argued to be made possible thanks to the introduction of a hafnium oxide (HfO2) layer between the silicon substrate and the vanadium oxide layer. Up to seven nearly identical VO2-based devices are contacted simultaneously to create a network of oscillators, paving the way for large-scale implementation of VO2 oscillating neural networks.
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Affiliation(s)
- Olivier Maher
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland.
- Institute of Neuroinformatics, University of Zürich and ETH Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
| | - Roy Bernini
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland
| | - Nele Harnack
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland
| | - Bernd Gotsmann
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland
| | - Marilyne Sousa
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland
| | - Valeria Bragaglia
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland
| | - Siegfried Karg
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803, Rüschlikon, Zürich, Switzerland.
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Wang D, Gao C, Wang Y, Chang X, Hu Y, Li J, Feng T, Dey JK, Roul B, Lu X, Du L, Zhai Z, Zhu H, Huang W, Das S, Su F, Zhu LG, Shi Q. VO 2 Films Decorated with an MXene Interface for Decreased-Power-Triggered Terahertz Modulation. ACS APPLIED MATERIALS & INTERFACES 2024; 16:10886-10896. [PMID: 38377567 DOI: 10.1021/acsami.3c16252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
VO2, which exhibits semiconductor-metal phase transition characteristics occurring on a picosecond time scale, holds great promise for ultrafast terahertz modulation in next-generation communication. However, as of now, there is no reported prototype for an ultrafast device. The temperature effect has been proposed as one of the major obstacles. Consequently, reducing the excitation threshold for the phase transition would be highly significant. The traditional strategy typically involves chemical doping, but this approach often leads to a decrease in phase transition amplitude and a slower transition speed. In this work, we proposed a design featuring a highly conductive MXene interfacial layer between the VO2 film and the substrate. We demonstrate a significant reduction in the phase transition threshold for both temperature and laser-induced phase transition by adjusting the conductivity of the MXene layers with varying thicknesses. Our observations show that the phase transition temperature can be decreased by 9 °C, while the pump fluence for laser excitation can be reduced by as high as 36%. The ultrafast phase transition process on a picosecond scale, as revealed by the optical-pump terahertz-probe method, suggests that the MXene layers have minimal impact on the phase transition speed. Moreover, the reduced phase transition threshold can remarkably alleviate the photothermal effect and inhibit temperature rise and diffusion in VO2 triggered by laser. This study offers a blueprint for designing VO2/MXene hybrid films with reduced phase transition thresholds. It holds significant potential for the development of low-power, intelligent optical and electrical devices including, but not limited to, terahertz modulators based on phase transition phenomena.
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Affiliation(s)
- Daoyuan Wang
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Chengzhe Gao
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Yunfeng Wang
- Key Lab of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Xue Chang
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Yiwen Hu
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Jiang Li
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Tangdong Feng
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Jayjit Kumar Dey
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Basanta Roul
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
- Central Research Laboratory, Bharat Electronics Limited, Bangalore 560013, India
| | - Xueguang Lu
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Lianghui Du
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Zhaohui Zhai
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Hongfu Zhu
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Wanxia Huang
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Sujit Das
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Fuhai Su
- Key Lab of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Li-Guo Zhu
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Qiwu Shi
- College of Materials Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, China
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Zhang C, Gunes O, Li Y, Cui X, Mohammadtaheri M, Wen SJ, Wong R, Yang Q, Kasap S. The Effect of Substrate Biasing during DC Magnetron Sputtering on the Quality of VO 2 Thin Films and Their Insulator-Metal Transition Behavior. MATERIALS 2019; 12:ma12132160. [PMID: 31284405 PMCID: PMC6650896 DOI: 10.3390/ma12132160] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/24/2019] [Accepted: 06/28/2019] [Indexed: 11/16/2022]
Abstract
In this work, VO2 thin films were deposited on Si wafers (onto (100) surface) by DC magnetron sputtering under different cathode bias voltages. The effects of substrate biasing on the structural and optical properties were investigated. The results show that the metal–insulator transition (MIT) temperature of VO2 thin films can be increased up to 14 K by applying a cathode bias voltage, compared to deposition conditions without any bias. The decrease in the transition efficiency and increase in the transition temperature are attributed to the enlarged grain size, increased defects, and the residual stress in the VO2 thin films induced by biasing. The optical transmittance measurements for different thickness films indicate an attenuation coefficient of 3.1 × 107 m−1 at 2000 nm or an extinction coefficient of 4.9 in the metal phase. The optical transmittance vs wavelength characteristics point to an indirect bandgap of 0.6 ± 0.5 eV and significant scattering in the bulk and/or at the interface.
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Affiliation(s)
- Chunzi Zhang
- Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - Ozan Gunes
- Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - Yuanshi Li
- Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - Xiaoyu Cui
- Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
| | - Masoud Mohammadtaheri
- Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | | | - Rick Wong
- Cisco Systems Inc., San Jose, CA 95134, USA
| | - Qiaoqin Yang
- Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - Safa Kasap
- Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada.
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