Making Graphene Work For Real-World Devices 18
aarondubrow writes: "Graphene, a one-atom-thick form of the carbon material graphite, is strong, light, nearly transparent and an excellent conductor of electricity and heat, but a number of practical challenges must be overcome before it can emerge as a replacement for silicon in electronics or energy devices. One particular challenge concerns the question of how graphene diffuses heat, in the form of phonons. Thermal conductivity is critical in electronics, especially as components shrink to the nanoscale. Using the Stampede supercomputer at the Texas Advanced Computing Center, Professor Li Shi simulated how phonons (heat-carrying vibrations in solids) scatter as a function of the thickness of the graphene layers. He also investigated how graphene interacts with substrate materials and how phonon scattering can be controlled. The results were published in the Proceedings of the National Academy of Sciences, Applied Physical Letters and Energy and Environmental Science."
No bandgap (Score:2, Informative)
Graphene - unlike silicon doesn't have a bandgap so the current in graphene can't be switched off. That leads to a poor transistor design.
Re:Why not just... (Score:4, Informative)
Aside from the bandgap issue (which does have workarounds), you basically guessed correctly. It's really damn hard to make a large sheet of graphene that will stick to a substrate properly, won't spontaneously fold into a nanotube, and doesn't have faults in the crystal structure.
It's actually pretty amazing, in comparison, what we've been able to do with silicon. We can produce chips with areas measured in square centimeters that are _perfect_ crystals all the way through. No impurities (except what we add), no faults in the crystal structure, just countless trillions of silicon atoms all in the correct place. And then we can pattern this silicon with multiple layers of intricate patterns with nanometer precision. And we can do this on an industrial scale to result in a chip that you buy for a hundred bucks.
Re:Why not just... (Score:5, Informative)
Silicon is an amazing material. It it cheap, plentiful, can be purified extremely well, are a natural semiconductor that can be doped easily, have a band-gap that makes creating transistors of many types easy, can be selectively oxidized and etched with high precision. There are many good reasons why computer chips are using silicon rather than other materials that may be faster (GaAs, InP etc.) as those are harder to work with in several ways including purity of the crystal, strength of substrate etc.
While graphene have certain advantages and are still researched intensively it also have a lot of problems. The making of graphene films have been made easier by different methods but they still can't be manufactured in bulk at a low price (unless I've missed something). It is also much harder to make transistors using it due to the bandgap issue. Processing of graphene is also not as developed as that of silicon and it isn't just a matter of process maturity (while that of course is one large reason) - silicon is simply easy to make things out of.
If graphene will ever be used in mass produced products it will most likely be in the form of graphene integrated on silicon wafers for conductors or other parts.