GNRs｜Integration Synthesis of Graphene Nanoribbon Quantum Dot Devices
In collaboration with Professor Otsuka and others at Tohoku University, we have demonstrated that by shortening the length of graphene nanoribbons synthesized using our method to the utmost, they exhibit behavior as graphene nanoribbon quantum dots. The results of this joint research show that well-defined levels and excited states in quantum dots can be observed up to relatively high temperatures. This demonstration serves as a crucial achievement, confirming that our integratable graphene quantum dot devices function effectively as high-quality quantum dots. We plan to further advance this research to facilitate practical applications in quantum integrated devices.
Communications Materials, Vol. 3, No. 103, pp. 1-7, 2022.12.22.
https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20230106_01web_graphene.pdf
GNRs｜Development of Thermoelectric Devices Utilizing Graphene Nanoribbons
In collaboration with Professor Li and colleagues at Kyushu University, we have demonstrated that the graphene nanoribbons synthesized by our method exhibit high thermoelectric performance. We attribute this to the intrinsic cleanliness of the synthesized edge structures. This discovery holds significant promise for future thermoelectric device applications.
ACS Nano, Vol. 13, No. 8, pp. 9182-9189, 2019.8.14.
GNRs｜Development of Non-Volatile Optical Memory Utilizing Graphene Nanoribbons
By irradiating the graphene nanoribbons synthesized using our method with oxygen plasma, we discovered that the graphene nanoribbons function as non-volatile memory. This phenomenon is attributed to the effect of persistent photoconductivity, where the current flowing through graphene is modulated by light irradiation. We have demonstrated the potential of utilizing graphene nanoribbons in novel devices through this effect, showcasing their capabilities in non-volatile memory applications. Scientific Reports,
Vol. 8, No. 11819, pp. 1-9, 2018.8.7.
https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20180808_01web_ribon.pdf
GNRs｜Large-Scale Integration Synthesis and Mechanism Elucidation of Graphene Nanoribbons
Through systematic experiments and comparison with theoretical models, we have elucidated the synthesis mechanism of graphene nanoribbons (GNRs) from Ni nanobars, which we uniquely developed. In this process, a highly efficient supply of hydrocarbon precursors from the plasma occurs within the liquid state Ni. During the cooling process, graphene nanoribbons precipitate on the surface of Ni nanobars, followed by the diffusion of liquid Ni from below to both ends. Optimizing the synthesis conditions based on this model, we successfully achieved the integrated synthesis of over one million graphene nanoribbons on a 2 cm square substrate with an efficiency exceeding 98%. This achievement represents a significant step toward realizing various device applications using graphene nanoribbons.
Nature Communications, Vol. 7, No. 11797, pp. 1-10, 2016.6.2.
https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20160602_01web.pdf
GNRs｜Development of Integration Synthesis Method for Graphene Nanoribbons
We have successfully developed a method for the position-selective synthesis of graphene nanoribbons (GNRs), which are one-dimensional structures of graphene. This approach involves preforming integrated devices and selectively synthesizing graphene nanoribbons only in the channel region, presenting a reverse idea compared to conventional methods. As a result, we discovered the direct synthesis of graphene nanoribbons from one-dimensional Ni (Ni nanobars) and successfully operated the graphene nanoribbons with a clean interface as field-effect transistors. This method, enabling large-scale integration of graphene nanoribbons with semiconductor properties, represents a significant achievement for the practical application of graphene nanoribbon devices in the future.
Nature Nanotechnology, Vol. 7, No. 10, pp.651-656, 2012.
https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20120903_02web.pdf
GNRs｜Direct Synthesis of Graphene onto Insulating Substrates
While the synthesis of graphene has traditionally occurred on metal surfaces like Ni or Cu thin films, we have discovered that using plasma CVD allows graphene to precipitate at the interface of an insulating substrate and a Ni thin film. By removing the surface Ni, it becomes possible to directly synthesize graphene on the insulating substrate without the need for a transfer process. This development holds promise for applications in integrated devices.
ACS Nano, Vol. 6, No. 10, pp. 8508-8515, 2012.
GNRs｜Selective Edge Functionalization of Graphene
We have successfully achieved selective nitrogen doping at the edges of graphene by irradiating it with mild plasma. This is a significant accomplishment from the perspective of controlling the functionality of graphene.
Small, Vol. 7, No. 5, pp. 574-577, 2011.
