Silicene takes on graphene as next transistor wonder-stuff University of Texas boffins have offered up another material they reckon is a hot bet for future generations of Moore's-law-beating super-fast transistors: silicene. Throwing its hat into the ring as an alternate to the popular wonder-stuff graphene, silicene – a single-atom-thick layer of silicon atoms – is, like graphene, …
"movement at the nanotech scale"
As anyone who did the O level physics Brownian Motion smoke experiment will know, molecule sized robots are likely to have great difficulty moving around unless they are significantly larger than the molecules forming the surrounding medium. Imagine building a tower block in continuous 24/7 golf ball sized hail storms except that large, heavy hail stones can come from any random direction.
@james68
As someone involved in the semiconductor industry whose employer makes hardware for the manufacture of graphene and other 2D materials, we aren't as far off as many seem to think.
A lot of the research is actually looking at other 2D materials, molydisulphide for example. Graphene is a useful buzzword at present that greatly increases the chances for researchers to get funding, but it is far more likely that other 2D materials with more specific application suitable properties (achievable on the same manufacturing hardware) will be the ones that actually get functionalised into devices.
AC for obvious reasons
"Still waiting to see real-world applications of graphene, though..."
Coming soonish to a Windows Phone near you:
http://www.nokiapoweruser.com/nokia-patents-self-charging-graphene-based-photon-battery-can-printed-flexible-substrates/
http://www.nokiapoweruser.com/nokia-may-commercialize-graphene-based-optical-sensors-soon/
"It's nanotech -- why would you expect to see it?"
I get it! Bit below the wavelength of light, right? :)
Nanotech is in use in every day life, the most obvious example being modern "micro"electronics, which fit firmly within the "nanoscale" of 1 to 100 nanometers. Nanoscale-material control is also common in materials engineering, achieved not with nanobots but with refinements of heat treating, purity control, chemical vapor deposition, and so on. You hear less about that boring stuff than nanobots, graphene, nanotubes, and other nanowonders, because the media seems educated by Hollywood and science fiction.
I hope that the structure is more regular than the picture in the article!
At the left-most end, we've got rectangular blocks of 6 silicon atoms in a 2x3 pattern, with adjacent blocks overlapping so that the middle of one of the x3 rectangles forms the corner of the adjacent rectangles.
At the right-most end, we appear to have pairs of silicon atoms forming the corners of a 2x2 square structure.
In the middle, it's all a bit of a mess, with some 'bonds' looking longer than others. I've not counted the bonds properly but the fact that silicon has a valance of 4 (the same as carbon) makes it look wrong. Maybe my chemistry is too rusty!
I suppose that it could be a problem with the projection, but I've looked hard, and I think the atoms are in the wrong place for it to be some form of aspect correction.
I keep looking, and I still can't make it work unless it is not purely 2D, and/or the 'units' are more like squashed hexagons than rectangles. Maybe I need to see a fully rendered model that I can rotate.
I had not spotted that the bonds were different colours (probably a problem with my monitor and the ambient light), so I suppose that the dark grey/black bonds are double bonds, and the lighter grey bonds are single. At least that makes the valence correct.
Since silicon atoms generally form four bonds, they are tetrahedral (as is carbon when forming single bonds). The typical shape of a six-membered ring is therefore either 'chair' or 'boat' shaped as in cyclohexane. To form a regular lattice, the configuration that tesselates is the 'chair' shaped one.
Graphene on the other hand, is composed of carbon atoms which are not forming 'single' bonds. Thyey are usually drawn as alternating single and double bonds, although the truth is that they are a hybrid of the two, as this configuration has a lower energy. The bonds in question are in a planar configuration, so graphene itself is truly flat. it is the special properties of the hybridisation of these bonds which leads to the delocalisation of the electrons, and the conductive properties of graphene.
I haven't seriously studied any chemistry for over a decade, but IIRC, the energy level of the bonds in silicon are close enough that they make it a semiconductor, unlike tetrahedral carbon (as in diamond, or in alkanes), which is an insulator.
Correct, it's not purely 2D -- the atoms aren't strictly in the same plane, but there is only one layer so it's a 2D material. If you look closely at the left part of the image you should see that the bonds from some atoms go slightly down while others go slightly up. Each of the holes in the lattice (when viewed from above) has 6 sides, so it's a honeycomb, and since the atoms are alternately a bit above or below their neighbours, it's a buckled honeycomb.
The US has absolutely robbed Asian countries of their best and brightest minds. Whilst American young-uns have their heads stuck in either a bong or a box, the young Asians are pouring out of US McUniversities in hordes. In many US corporations a significant fraction of the meetings are no longer held in english, with Hindi being the linga Franca.
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