Self-aligned 2D material ribbons and plasmonic nanobelts

The project entitled Self-aligned 2D material ribbons and plasmonic nanobelts is set to explore two novel approaches in bottom-up patterning of two-dimensional (2D) materials, and to understand the basic mechanisms behind the proposed methods. By growing self-assembled and self-aligned organic nanostructures and using those as masks, we plan to fabricate large-area nanoribbon networks of arbitrary 2D materials. We will explore several methods for etching of 2D materials (plasma etching, laser ablation) with the goal to imprint the patterns provided by the self-assembled organic nanostructures. Further, we intend to use these nanoribbon networks as templates/scaffolds for fabrication of highly ordered plasmonic arrays and nanobelts, through edge-decoration with metallic nanoparticles (NPs) by bottom-up chemical synthesis methods. The project is expected to break new grounds in nanoscale patterning of 2D materials by bridging between self-assembly and self-alignment on the atomic scale with large-area patterning of arbitrary 2D materials. Although the growth of organic semiconductors on 2D materials is well understood, proposed approach in organic self-assembly based lithography has never been applied before. Having high level of control over the fabrication of these hybrid nanostructures will allow better understanding of their structure-property correlation. As a result, we envision to discover electron-plasmon interference phenomena in 2D materials that has never been explored before, especially with our expertise in nano- optical and nano-electrical characterization. Since the proposed project will open new directions in large-area bottom-up patterning of arbitrary 2D materials, it will also enable development of disruptive technologies. Having large-area nanostructured 2D materials with extremely high edge-to-surface ratio is very interesting for future development of sensing technologies as: chemical and plasmonic sensing, multi-sensing chips, e-skin; and for photodetectors applications as: high-speed data transmission, quantum cryptography, and computing. Thus, the project results will go beyond the scientific community, eventually reaching consumer electronics and influencing consequently our daily life.

The project "Self-aligned 2D material ribbons and plasmonic nanobelts" was realized in the time period 2020-2023 between the research teams of Priv. Doz. Dr. Aleksandar Matkovic from Montanuniversitaet Leoben in Austria and Prof Raul David Rodriguez from Tomsk Polytechnical University n Russian Federation. Although the project was implemented in a very turbulent timeframe, with global pandemics and Russian-Ukrainian crisis, the research teams managed to maintain the collaboration and to develop set project goals. The project is set in the field of two-dimensional (2D) materials for electronic, plasmonic and catalysis applications. Todays microchips are shrinking to the level where only few thousand atoms are contained in the main functional switching elements (transistors). Since 2025 it is expected that silicon based commercial technologies will go toward silicon nanoribbons, and that this new architecture will likely be sufficient to enable the needed electronics industry growth until 2032. Afterwards, it is likely that microelectronics might have to be based on non-silicon materials for the core elements. This is where 2D materials are likely to come into the field. From that perspective, research has to be done now, and fabrication not only of 2D material layers but also nanoribbons has to be explored and most suitable methods established. The goal of the project was to develop a new method for fabricating nanoribbons, atomically thin and only few tens of nanometer wide strips. The teams have proposed to use self-assembly of organic molecules on 2D materials and their use as nanoscale patterning masks. This approach was never tested before, and it turned out to be a successful pathway. Prepared electronic devices from 2D material nanoribbons via this novel method were first reported by this project in 2022, and to date they hold the record in nanoribbon electrical performance. Chosen organic structures inherently form nanoscale objects at the length scales comparable to DNA molecules, and well below the limits of modern lithography. At the same time the proposed method is scalable and could be adopted to work on the scale needed for the in-line production of thousands of microchips. Furthermore, besides the proof-of-principle that the method is suitable for nanoelectronics, the project has also explored the applicability of these nanoribbons in plasmonics (nanoscale confined light) and catalysis. The teams demonstrated that it is possible to form metallic nanoparticles (only few nanometers in diameter) that grow exclusively from the edges of nanoribbons. The hybrid mixed-dimensional nano-system was called plasmonic nanobelt, as the ribbons appear decorated with particles along their edges. These nanobelts have demonstrated plasmonic enhancement of light and extreme catalytic efficiency. Therefore, the project has opened several new directions in nanofabrication, controllable catalysis, and plasmonic sensing.