The new method creates nanomaterials with a precision of fewer than 10 nanometers. This could open the door to faster and more efficient electronics.
Researchers at DTU and Graphene Flagship have elevated the art of nanomaterial patterning to a new level. The precise patterning of 2D material is a way to compute and store using 2D materials. This can provide better performance and lower power consumption than current technology.
Two-dimensional materials like graphene are one of the most important discoveries in physics and material tech. Graphene is more potent than any other known material and can conduct heat and electricity better.
The best thing about these materials is their ability to be programmed. We can modify the properties of these materials by creating intricate patterns and making exactly what we want.
DTU scientists have improved the state-of-the-art patterning 2D materials for over a decade using sophisticated lithography machines in a 1500m2 cleanroom facility. The Center for Nanostructured Graphene at DTU is where they work. The Graphene Flagship and the Danish National Research Foundation support it.
DTU Nanolab’s electron beam lithography system can record details as small as 10 nanometers. Computer calculations can accurately predict the size and shape of graphene patterns to create new types of electronics. These calculations can use the charge of an electron and quantum properties like spin or valley degrees-of-free to make high-speed calculations that consume far less power. However, these calculations require a higher resolution than any lithography system can provide: atomic resolution.
Peter Boggild, professor at DTU Physics and group leader, says, “If we want to unlock the treasure trove for future quantum electronics,”
This is precisely what researchers achieved.
“In 2019, we demonstrated that semimetallic graphene can be made into a semiconductor by placing circular holes with a spacing of 12 nanometers. We now know how to make circular holes and other shapes like triangles with nanometer-thin corners. These patterns help sort electrons based on their spin and can be used to create crucial components for spintronics and valleytronics. This technique can also be applied to other 2D materials. Peter Boggild explains that these super-small structures can make electrically tunable metalenses for high-speed communications and biotechnology.
Razor-sharp triangle
Lene Gammelgaard (an engineering graduate from DTU in 2013) led the research and has played a crucial role in DTU’s experimental exploration of 2D material.
“The trick is to place nanomaterial hexagonal boron-nitride over the material you wish to pattern. Lene Gammelgaard continues, “Then drill holes using a specific etching recipe.”
“The etching processes we have developed over the years reduce patterns to a size below our electron beam-lithography systems’ unbreakable limit of 10 nanometers. Let’s say we create a circular hole of 20 nanometers in diameter. The gap can then be reduced to 10 nanometers in graphene. If we make a triangle-shaped hole with the holes from the lithography, the downsizing will result in a smaller triangle and sharp corners. Patterns are easier to make if they’re smaller. This is not the case and allows us to create the structures that our theoretical predictions say are optimal.
You can, for example. Flat electronic meta-lenses can be made- a super-compact optical lens that can be controlled at extremely high frequencies. According to Lene Gammelgaard, these lenses can become vital components of future communication technology.
Pushing the boundaries
Dorte Danielsen, a young student, is the other key person. After a nine ninth-grade internship in 2012, she became interested in nanophysics. She was selected in the final national science contest for high school students in 2014. In 2014, she pursued studies at DTU’s honors program.
She explained that it is still unclear what the mechanism behind “super-resolution structures” is.
We have many theories about the unexpected behavior of etching, but we still don’t know everything. It is still an exciting and beneficial technique. It is also good news for thousands of researchers pushing the boundaries in 2D nanophotonics and nanoelectronics worldwide.”
Dorte Danielsen, who the Independent Research Fund Denmark supports in the METATUNE program, will continue to work on nanostructures with extremely sharp edges. The technology she developed will be used here to create and explore electrically-tuneable optical metalenses.
