Manufacturing Techniques for Graphene Become More Sophisticated
Research refines the ability to produce single-crystal graphene in bulk and calls upon an old chip making technique to make it impermeable to the elements
We have dedicated a fair amount of cataloguing and chronicling to the developments in manufacturing graphene.
The key with graphene production is finding a way to make a lot of it while maintaining its extraordinary properties. Unfortunately, for the most part, these two interests have remained mutually exclusive.
Chemical vapor deposition (CVD) has been held out as the best hope of getting scalability and purity combined in graphene production. However, this technique requires that the graphene be grown on metal substrate, like copper, and then later peeled off the substrate. This peeling process often results in the graphene either being completely ruined or at the very least contaminated.
Now researchers at the University of Groningen in the Netherlands have developed a production method based on CVD that eliminates the potential for ruin or contamination while still remaining scalable. It is based on something the researchers noticed when analyzing CVD-grown graphene three years ago.
“When we analyzed a sample of graphene on copper, we made some strange observations,” said Meike Stöhr, one of the researchers, in a press release.
The researchers saw that copper oxide was present next to the copper. The graphene had formed a kind of protective dome on top of the copper oxide. The researchers knew that a process in electronics manufacturing known as passivation used a light coat of a protective oxide to create a shell against corrosion.
From this observation, the researchers deduced that the copper oxide layer could leave the graphene’s properties intact. So, in research published in the journal Nano Letters, the researchers grew graphene directly on copper oxide. The result of this growth method was that decoupling the graphene from the copper oxide preserved all of graphene’s electronic properties.
Encapsulation Enables Graphene To Survive Real-World Environments
Spain-based Graphenea SE (the CEO of which we interviewed for this edition of the newsletter) and AMO GmbH in Germany have developed a sophisticated encapsulation technique that should allow graphene devices to survive in normal atmospheres for several months, according to the companies.
The German-Spanish team added a small twist to the passivation techniques in which a protective oxide is used to create a shell against corrosion. In their encapsulation method, they grew the oxide layer using an oxidized layer of aluminum that served as the seed for further growth.
The result of this little twist to the passivation technique meant that the graphene device remained stable in ambient atmospheres for several months.