Going mass market with Graphene

Progressively zoomed-in images of graphene nanoribbons grown on germanium (gray area). The ribbons automatically align perpendicularly and naturally grow in “armchair” edge configuration. Credit: Arnold Research Group and Guisinger Research Group

Graphene is sometimes seen as the holy grail for the semiconductor industry, able to replace silicon and drive the electronic industry into the next decade.

It is an excellent conductor and it has very good heat dissipation capability. It is not a semiconductor but it can become a semiconductor by inserting certain atoms (like it happens with silicon when we want to use it for optical fibre -erbium doped-  or in very fast radio transmission -gallium arsenide doped.

The problem is to find a way to manufacture graphene using an industrial process with high yield and at low cost.

This is what researchers at the University of Wisconsin-Madison are working on. They have found a way to grow graphene nano-ribbons directly on a conventional germanium wafer.

The process for growing the graphene nano-ribbons directly on the germanium is compatible with the present planar processing used by semiconductors manufacturing industry. Additionally the creation of nano ribbons, 10nm wide, so far has ben achieved by cutting large (relatively speaking) foils of graphene but the cut produces rough edges and this is not allowing a continuous bonding of the carborn atoms at the edges with the silicon/germanium substrate. 

On the other hand by using a bottom up approach, typical of nanotech, they managed to form the nano ribbons of graphene directly on the germanium surface. To do this they use a vapour deposition technique. By subjecting the germanium surface to methane vapours in presence of graphene crystals they observed a spontaneous growth of graphene into nano ribbons. By regulating the flow of methane they manage to create nano ribbons of the desired width. 

The next problem to solve to allow mass production is the find a way to make sure the deposition of each nano ribbons happens exactly where it is needed.

Author - Roberto Saracco

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