04 April 2014

Samsung’s graphene breakthrough could finally put the wonder material into real-world devices

A graphene wafer, being tested at IBM
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 so stick with me while I try to explain it. 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
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 (yes, I enjoyed writing that) 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. [Research paper: DOI: 10.1126/science.1252268]. 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).

wafer of graphene chips at IBM Research
Wafer of IBM’s graphene chips. This photo, and the one at the top of the story, are unrelated to the Samsung breakthrough. They’re just awesome photos.

So far, it seems Samsung has used this new process of growing graphene to create some field-effect transistors (GFETs), which performed quite well, but that’s about it. Still, in a press release, Samsung pulls no punches: “This is one of the most significant breakthroughs in graphene research in history,” said the SAIT researchers. This being Samsung, of course, the press release also talks about how graphene is “the perfect material for use in flexible displays, wearables and other next generation electronic devices.”

These claims might sound hyperbolic, but to be fair this is probably the most exciting graphene breakthrough that I’ve written about in the last three years. This process gets us very close to commercial, large-scale production of high-quality, electronics-grade graphene. This doesn’t mean that we’ll suddenly see computer chips made out of graphene instead of silicon, though we still haven’t found a way of giving graphene a bandgap, which means it’s actually fairly useless as far as digital computing goes.

Credit: Extremetech

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