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Graphene has offered scientists and engineers new possibilities for optical, electronic, and mechanical materials. There are widespread graphene research activities happening across the globe since it was discovered in 2004. Now, researchers from the National University of Singapore (NUS) have found a way to grow and transfer graphene with very few defects.
One of the many areas graphene has been used in is to create transparent conductive films for touch screen panels of electrodes. However, producing wafer-scale graphene films that is of pristine quality is plagued by a few challenges. One of these challenges is the ability to grow and transfer graphene with very few defects for use in semiconductor industries.
Professor Loh Kian Ping and his research team from the National University of Singapore (NUS) have recently found a solution.
The team have developed a novel method to grow and transfer graphene on silicon and other stiff substrates with very high quality. The success of their project has led to numerous opportunities for graphene to be applied in high-end applications that have so far not been technologically viable.
Bio-Inspired Method of Graphene Production
The NUS team was able to achieve creation and transfer of graphene on silicon and other stiff substrates after being inspired by nature – specifically the amazing ability of beetles and tree frogs to keep their feet attached to submerged leaves.
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They grew graphene on a copper catalyst layer that coated a silicon substrate. Once the growth was achieved, the copper was etched away. The graphene continued to remain in place, held by bubbles that form capillary bridges, which is comparable to the feet of beetles and tree frogs attached to submerged leaves. The capillary bridges aided in keeping the graphene on the silicon surface and preventing its delamination during the etching of the copper catalyst. Gradually, the graphene became attached to the silicon layer.
For enabling the formation of capillary bridges, the team introduced gases into the wafer as a pre-treatment step. This helped alter the properties of the interface and assist the formation of capillary bridges during the penetration of a catalyst-removal liquid. A surfactant is added to smooth folds and creases caused by the transfer process.
Possible Applications
The bio-inspired method of graphene production has drawn widespread attention as it opens up the possibilities to numerous applications. Using this method, graphene can be used in photonics and electronics - for devices such as transistors, on-chip biosensors, tunneling barriers, and optoelectronic modulators.
It will also help speed up the development of graphene-on-silicon platforms to a great extent.
Next Step
The bio-inspired graphene production method developed by the NUS team is open for improvement so that it can be adapted for use in batch-processed semiconductor production lines, e.g. in fabrication of large-scale integrated circuits on silicon wafers.
The next step planned by the NUS team is to optimize the method so as to realize high throughput production of large diameter graphene on silicon, and aim at particular graphene-enabled applications on silicon. The team also plans to use the method on other 2D films.
With graphene production taking another positive leap, the miracle material is likely to be around for many more years to come.
Sources and Further Reading