Nanolithography Of Two-Dimensional Materials

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Researchers developed a new method for designing nanomaterials with less than 10-nanometer precision, opening the way for faster, more energy-efficient electronics.

Two-dimensional materials such as graphene are one of the most significant promising materials for future electronic devices. Graphene is stronger, smoother, lighter, and better at conducting heat and electricity than any other known material. 

Most unique property of these materials is their programmability. By creating delicate patterns in these materials, we can change their properties dramatically and possibly make precisely what we need. This patterning must be precise for achieving high-performance. 

Researchers from Technical University of Denmark and Graphene Flagship have developed a new method for patterning nanomaterials. The patterning is done using sophisticated lithography machines. AT DTU, the lithography machine can write details down to 10 nanometers. 

The computer calculations can accurately determine the shape and size of patterns in the graphene to create new types of electronics. The researchers can exploit the charge of the electron and quantum properties such as spin or valley degrees of freedom, leading to high-speed calculations with far less power consumption.

However, these calculations require higher resolution at an atomic level. And researchers have succeeded in achieving that resolution.

“We showed in 2019 that circular holes placed with just 12-nanometer spacing turn the semimetallic graphene into a semiconductor. Now we know how to create circular holes and other shapes such as triangles, with nanometer sharp corners. Such patterns can sort electrons based on their spin and create essential components for spintronics or valleytronics. The technique also works on other 2D materials. With these supersmall structures, we may create very compact and electrically tunable metalenses to be used in high-speed communication and biotechnology,” explains Peter Bøggild.

“The trick is to place the nanomaterial hexagonal boron-nitride on top of the material you want to pattern. Then you drill holes with a particular etching recipe,” says Lene Gammelgaard, and continues:

“The etching process we developed over the past years down-size patterns below our electron beam lithography systems’ otherwise unbreakable limit of approximately 10 nanometers. Suppose we make a circular hole with a diameter of 20 nanometers; the hole in the graphene can then be downsized to 10 nanometers. While if we make a triangular hole, with the round holes coming from the lithography system, the downsizing will make a smaller triangle with self-sharpened corners. Usually, patterns get more imperfect when you make them smaller. This is the opposite, and this allows us to recreate the structures the theoretical predictions tell us are optimal.”

The research has been published in the journal ACS Applied Materials & Interfaces.


 

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