TAIPEI (Taiwan News) — In view of rising demand for quantum technology beyond CMOS, a research team at Taiwan's Cheng Kung University (NCKU) has invented a groundbreaking method to re-engineer graphene which is believed to be a breakthrough in both fundamental physics and technological applications.
Taiwan's Ministry of Science and Technology (MOST) recently held a press conference to applaud the achievement. Luo Meng-fan (羅夢凡), the ministry's director general of Dept. of Natural Sciences and Sustainable Development, said that the development has drawn wide attention due to its commercial potential in the electronic components market.
Luo Meng-fan (third from right) pointed out the technique is unique and significant at a press conference in late March, 2021 (CNA photo)
The researchers were able to re-engineer graphene, which is soft and conducts electricity easily, by adjusting the distance and arrangement of atoms with assistance of electron-beam lithography and dry etching to achieve artificial lattice deformation through patterned strain engineering in two-dimensional (2D) materials.
In recent years, researchers have been focused on stacking layers of graphene (or other atomic-thin 2D materials) at the nanoscale level like LEGO building blocks. By twisting these atomic LEGO blocks, scientists around the world had been able to adjust the lattice structure allowing them to transform graphene from a zero-gap semiconductor into a superconductor, an insulator, or a ferromagnet.
However, stacking 2D materials at the atomic level can be extremely difficult, posing difficulties for scalability and future industrial applications. This led Ho Sheng-Chin (何昇晉) and Chen Tse-Ming (陳則銘) to come up with the idea to artificially create the superlattice in bilayer graphene through nanofabrication.
The team was able to develop the new technique to selectively etch the surface of hexagonal boron nitride substrates into arbitrary geometric patterns, allowing graphene to be placed upon it to conform to the surface topography and be strained accordingly. One advantage of this approach is that the substrate topography can be arbitrarily defined through nanolithography with the potential to approach 2.5D and 3D patterning, thereby opening up more possibilities.
Chang Ching-Hao (張景皓) was responsible for developing the theoretical model and performing the calculations with colleagues to lay down the foundation for Ho and Chen’s work. The theory completed the last piece of the puzzle, demonstrating several unusual and nontrivial quantum properties and phenomena.
These novel electronic properties are useful to drive innovation in future electronics, for example, it challenges the conventional wisdom on how the electrical signal can be transmitted and thus may lead to new design principles in electronic devices.
Their work was published in Nature Electronics February 2021 edition.
National Cheng Kung University has been active in research and development and is the cornerstone for the country's technological innovation. The new findings are expected to make Taiwan more competitive in the field of quantum technology.