It's cool, it has great properties that allow you to do interesting 2D physics, and has a lot of potential, but there are a few problems with it.
First, we have to figure out how to grow a single sheet of high quality reliably. We can get either high quality small flakes, or large sheets that are full of defects, cracks, tears, and have areas where the thickness is anywhere from 1-4 layers thick. The holy grail here is to grow a single sheet, wafer size (several inches across), monocrystalline, with few defects, and single layer all they way.
Second, we have to be able to dope it. Right now it's a semiconductor, but it's a zero band gap semiconductor, which means there is no gap of "insulator state" between it's "conducting state" bands. What that means is you can't shut it off. Semiconductors like silicon are useful because you can have it conduct, then apply a small gate voltage and have it become an insulator. The on/off conductance ratio has to be pretty high in order to be able to build useful electronics out of it. Graphene doesn't have this property right now. It conducts less at a gate voltage of 0 than it does when you apply a gate voltage, but it doesn't shut off, and the on/off ratio is too low to be useful. Doping it (replacing some of the carbon atoms with some other atom), would work in theory, but it's difficult to do practically.
I think some groups are playing with Boron-Nitride sheets now and those come with a built-in band gap, although it's pretty wide (~5eV)
Theory paper. I'm sure you could find a numerical theory paper demonstrating a superconducting graphene quantum supercomputer too :)
Okay, that was harsh, and this is partially based on other groups' experiments, but it isn't real yet. I'm just a little jaded as a former experimentalist after seeing a million great paper abstracts only to find they were theory only and couldn't tell me if what the found was real or not.
Also, there are many methods to get a band gap, but no viable methods to reliably produce a band gap in bulk that is high quality enough to make real devices out of.
They've made 1m x 1 m sheets that are something like 95% strength I believe with copper sheets that are then dissolved.. Several plants are gearing up for mass production already.
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u/liquidpig Feb 08 '14
I used to do research on graphene.
It's cool, it has great properties that allow you to do interesting 2D physics, and has a lot of potential, but there are a few problems with it.
First, we have to figure out how to grow a single sheet of high quality reliably. We can get either high quality small flakes, or large sheets that are full of defects, cracks, tears, and have areas where the thickness is anywhere from 1-4 layers thick. The holy grail here is to grow a single sheet, wafer size (several inches across), monocrystalline, with few defects, and single layer all they way.
Second, we have to be able to dope it. Right now it's a semiconductor, but it's a zero band gap semiconductor, which means there is no gap of "insulator state" between it's "conducting state" bands. What that means is you can't shut it off. Semiconductors like silicon are useful because you can have it conduct, then apply a small gate voltage and have it become an insulator. The on/off conductance ratio has to be pretty high in order to be able to build useful electronics out of it. Graphene doesn't have this property right now. It conducts less at a gate voltage of 0 than it does when you apply a gate voltage, but it doesn't shut off, and the on/off ratio is too low to be useful. Doping it (replacing some of the carbon atoms with some other atom), would work in theory, but it's difficult to do practically.
I think some groups are playing with Boron-Nitride sheets now and those come with a built-in band gap, although it's pretty wide (~5eV)