On March 28th, a groundbreaking method for growing graphene nanoribbons was unveiled by a collaborative team including Professor Shi Zhiwen from the School of Physics and Astronomy at Shanghai Jiao Tong University, Professor Michael Urbakh from Tel Aviv University, Professor Ding Feng from the Shenzhen Institute of Advanced Technology, and Professor Ouyang Wengen from Wuhan University. This new technique allows for the embedded growth of ultra-high-quality graphene nanoribbons between layers of boron nitride, creating an "in situ encapsulated" graphene nanoribbon structure. Demonstrations have shown that these grown graphene nanoribbons can be utilized to construct high-performance field-effect transistor (FET) devices. The research has been published online in the journal Nature.
The ultimate performance of semiconductor devices largely depends on the mobility of carriers within the semiconductor material. Graphene, a two-dimensional crystal composed of a single layer of carbon atoms arranged in a honeycomb lattice, boasts a unique electronic band structure and exceptional electronic properties, with a carrier mobility that can exceed that of silicon by more than a hundredfold. Carbon-based nanoelectronics, predicated on graphene, promise to usher in a new era for the information society.
Graphene nanoribbons that simultaneously possess a bandgap and ultra-high mobility are among the ideal candidate materials for carbon-based nanoelectronics. However, the challenge of fabricating high-quality graphene nanoribbons suitable for semiconductor devices has yet to be resolved. Numerous studies indicate that encapsulating graphene within boron nitride enhances various properties significantly. Yet, the efficiency of existing mechanical encapsulation methods is too low to meet the needs of scaled production in the future advanced microelectronics industry.
To address these challenges, the research team developed an innovative fabrication method that achieves the embedded growth of graphene nanoribbons between boron nitride layers, resulting in a distinctive "in situ encapsulated" semiconducting graphene nanoribbon. Observations reveal that the growth of graphene nanoribbons occurs exclusively at the catalyst particles, and throughout the process, the position of the catalyst remains unchanged. Building on this, the team established a detailed experimental model and systematically simulated the slipping process of graphene nanoribbons between boron nitride layers through molecular dynamics simulations and first-principle calculations. It was found that for the same magnitude of applied force, the distance that nanoribbons insert into the boron nitride layers is significantly greater than the distance they move on the surface, indicating that slipping graphene nanoribbons between layers of hexagonal boron nitride is unexpectedly easier than on its surface. Further, researchers created field-effect transistor (FET) devices based on the interlayer-grown nanoribbons, with the graphene nanoribbon FETs exhibiting typical semiconductor device electrical transport characteristics and carrier mobilities surpassing those reported previously.
The graphene nanoribbon transistor with "in situ encapsulation." Image source: Nature.
Related paper information: https://doi.org/10.1038/s41586-024-07243-0
