Breakthrough in the field of graphene devices

graphene growing on germanium

Samsung appears to have stumbled across the holy grail of commercial graphene production: A new technique that can grow high-quality single-crystal graphene on silicon wafers — graphene that is suitable for the production of graphene field-effect transistors (GFETs) — and afterward, once the graphene has been peeled off, the silicon wafers can even be reused! Samsung is dressing this up as a breakthrough for flexible, wearable computers — which is fair enough, given the company’s recent focus on curved smartphones and watches.

This work, carried out by the Samsung Advanced Institute of Technology (SAIT) and Sungkyunkwan University in South Korea, is rather advanced. Basically, they start with a normal silicon wafer. They coat the wafer in a layer of germanium (Ge), and then dip the wafer in dilute hydrofluoric (HF) acid, which strips off the native (naturally forming) germanium oxide groups, leaving a “sea” of hydrogen atoms that are bonded to the germanium underneath (H-terminated germanium, in chemistry speak). The wafer is then placed into furnace, where fairly normal chemical vapor deposition (CVD) is used to deposit a layer of graphene on top of the H-terminated Ge. Finally, after a bit more baking, and cooling under vacuum, the graphene is ready to be peeled off and used in the fabrication of graphene transistors and other such devices.

Graphene growing on H-terminated germanium. The orange circles are germanium, the little blue dots are hydrogen, and the black dots are carbon (graphene)

Importantly, the graphene monolayer monocrystals grown in this way are wrinkle-free — and because the graphene is removed from the germanium using a dry process, it is high quality and low in defects, too.
Also significant is the fact that the silicon wafers and germanium substrate can be reused and recycled (currently, the most popular method of producing graphene is on a copper substrate, which is then wastefully burnt away with acid).

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