Researchers have revealed a new method that enables laboratory scanning electron microscopes to observe graphene growing over a microchip surface in real time.
This discovery by a team at Surrey University could be a significant step closer to mass commercialisation and production of graphene for electronic devices. Their findings are detailed in ACS Applied Nano Materials.
Using video imagining, the team from Surrey’s Advanced Technology Institute (ATI) have shown graphene growing over an iron catalyst, using a silicon nitride membrane produced within a silicon chip. The membrane is only a few tens of nanometres thin, and heating and cooling can be rapidly controlled by means of modulating an electrical signal that is sent to the iron layer. This acts as a catalyst and as an electrical resistor to supply the heat.
The imaging is said to use Fermi-level contrast to visualise doping levels of graphene. This contrast mechanism can be used to identify the point of electrical contact between neighbouring graphene flakes. This imaging reveals also that physical contact alone between flakes is not sufficient to form electronic contact, which suggests additional bonding is required before electrons are able to jump from flake to flake.
In a statement, Professor Ravi Silva, director of ATI and Head of the Nano-Electronics Centre at Surrey University, said: “Graphene, the wonder material of the 21st century, has had much written about its unique and remarkable properties over the last decade. It will be widely used if it can be handled expertly and placed easily in applications.
“To do this, there need to be routes of observing graphene and precisely placing it on devices. In the research paper, one such route – using a standard electron microscope found in most well-resourced laboratories – is exemplified. We hope this work will encourage many more applications and discoveries of graphene for practical use.”