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Graphene breakthrough threatens silicon's chip glory20 Dec 2007 09:57 This time they mean it"For years graphene has proved a cruel temptress for the semiconductor avant garde."By Senor Beavis
Posted Thursday 20th December 2007 10:12 GMT
I vote this to be 2007's most pretentious opening gambit for an article. Well done! At this rate Ashlee, you'll end up being quoted in Private Eye... (good/bad in equal measure) Hole flowBy Sam
Posted Thursday 20th December 2007 11:28 GMT
...is the opposite direction to electron flow, if I remember correctly. Musical holesBy Dave Jones
Posted Thursday 20th December 2007 17:00 GMT
Hole flow is simple enough to visualize. Take a row of seats filled with bums except for one seat. Person next to the empty seat moves into it, leaving their own seat empty. Next person does the same, etc. The "empty seat" flows in the opposite direction to the bums. Semiconductors come in N-type where some atoms have a spare electron and P-type where some atoms are short one electron. In P-type semiconductors the atoms with the deficiency are called "hole sites". Apply a voltage to a P-type and electrons flow by jumping into holes, leaving holes behind them, etc. The holes "flow" in the opposite direction. Hole FlowBy Nick Oakley
Posted Thursday 20th December 2007 17:57 GMT
Yup, the holes are the conceptual spaces left behind as each electron jumps to the next space that its neighbour has just vacated in a weird kind of marble-solitaire way. Early discoverers of electricity had to guess which way the current flowed and they guessed wrong, so that conventional current is always described in diagrams as flowing from positive to negative in the same direction that the holes appear to move. Electrons actually flow from negative ( cathode ) to positive ( anode ) in the opposite direction. Cell phones and high power output ?By Anonymous Coward
Posted Thursday 20th December 2007 20:48 GMT
Somebody call Mothers Against Cell Phone Cancer ! They're gonna make our brains melt if we don't pay attention ! Last time I heard "Hole Flow"...By Michael Hoenig
Posted Thursday 20th December 2007 20:57 GMT
...had to be around '74, when the USAF was teaching me everything I didn't yet know about electronics. Darned Heathkit never mentioned holes, but they clearly indicated current flow was opposite to electron flow; my, how much I learned back then :D and had forgotten since! Im still a bit put off by a void (hole) being the carrier of current...my brain has successfully wrapped itself around the concept, but it still reeks of error! Graphene?By GrahamT
Posted Friday 21st December 2007 12:12 GMT
I always wondered when Carbon would be used for semi-conductors, as it is next in line in the periodic table after germanium and silicon, but I always assumed it would be the crystaline form, (as are semi-conductor germanium and silicon) i.e. diamond. I guess graphite is a crystal, but only in two dimensions. DiamondBy Mage
Posted Friday 21st December 2007 14:09 GMT
Substances that conduct heat and insulate electricity well are rare. Beryllium Oxide is one, (and dangerous, used to insulate RF transistor collector/Substrate from heatsink to allow emitter to be earthed). Diamond is also unusual in that it is an excellent heat conductor but also a good insulator. Hence the diamond allotrope of carbon is no use as a semiconductor. It's also difficult to grow diamond crystals the size fab labs are used to with silicon :-) Graphene and nano-tube carbon structures can though make devices. The period for commenting on this story has finished |
Breaking Reseller News
NEC Computers yesterday signalled its intent to become 100 per cent indirect in the UK over the next year.
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