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Ohm's Law Survives To the Atomic Level
Hugh Pickens writes "Moore's Law, the cornerstone of the semiconductor industry, may get a reprieve from its predicted demise. As wires shrink to just nanometers in diameter, their resistivity tends to grow exponentially, curbing their usefulness as current carriers. But now a team of researchers has shown that it is possible to fabricate low-resistivity nanowires at the smallest scales imaginable by stringing together individual atoms in silicon as small as four atoms (about 1.5 nanometers) wide and a single atom tall. The secret is to introduce phosphorus along that line because each phosphorus atom donates an electron to the silicon crystal, which promotes electrical conduction. They then encase the nanowires entirely in silicon, which makes the conduction electrons more immune to outside influence. By embedding phosphorus atoms within a silicon crystal with an average spacing of less than 1 nanometer, the team achieved a diameter-independent resistivity, which demonstrates ohmic scaling to the atomic limit. 'That moves the wires away from the surfaces and away from other interfaces,' says physicist says Michelle Simmons. 'That allows the electron to stay conducting and not get caught up in other interfaces.' The wires have the carrying capacity of copper, indicating that the technique might help microchips continue their steady shrinkage over time and may even extend the life of Moore's Law. 'Fundamentally, we have shown that we can maintain low resistivities in doped silicon wires down to the atomic scale,' says Simmons, adding that it may not be ready for production now, but, 'who knows 20 years from now?'"
If the atomic resistance gather together at ohm's law, will they occupy it?
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... it scale and can you produce it cheaply?
Since the popular definition of Moore's Law is exponential growth in any tech-related field, I'd say approximately never..
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They're different laws about different things, they just happen to relate in this instance.
+1 IDisagreeSoHeMustBeATrollOrAnAstroturferOrAShill
At what point will we stop hearing about it?
When you stop reading a site dedicated to geeks, computer professionals and computer enthusiasts.
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My only issue with Moore's law is that it's a "Law", when really it's more of a guideline. If it was truly a law, then semiconductors would half in size naturally over time, without any research or development involved. Plus I believe that the "Law" gets regularly adjusted as the trend declines.
+1 IDisagreeSoHeMustBeATrollOrAnAstroturferOrAShill
Of course it's valid. It's a law! Not some phony-baloney "theory" like evolution or gravity.
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TFA says that the wires were deposited lithographically (the technique currently used to make chips) and then the phosphorus was deposited. So this, in theory, could be done cheaply.
However, TFA also mentions low temperature. It doesn't measure exactly what temperature, but processors are not usually operated at low temperatures. If this is a "liquid nitrogen cold" temperature, then this could very well be useless on a grand scale. But if the effect survives to room temperature (or higher), then this could have a huge impact.
Just a first order approximation would show that these wires are about 5 times smaller than the current 22nm state-of-the-art. In two dimensions, that means roughly a 2500% increase in density, enough to keep Moore's law alive and well for some time to come.
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The resistance of interconnects grows polynomially, not exponentially, as they decrease in size.
It's an important difference. As sizes get small enough, we start to see stochastic effects, but we're not there yet.
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You learned Moore's "law" in high school physics class? That seems pretty off-topic to me.
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Likely because I just quit smoking and are somewhat grumpy, but I am tired of hearing about Moore's Law. Maybe those in the semiconductor industry care about it, but I, and those I work with certainly don't. At what point will we stop hearing about it? /rant
(Thank you for your patience. Now where are the damn pretzels?)
The most important part of Moore's Law was it essentially saying that your new toy will be far better than your old one before it even breaks. When the rate of doubling gets closer to 10 years, buying a new computer isn't going to be so much as the new toy is faster but rather the old toy broke. Once that driving force is over with, electronic companies will be talking about other ways to produce money in more mundane ways.
Except silicon crystals are opaque and metallic in appearance. Besides, computers are already full of silicon crystals.
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Seeing that the doubling power in Moore's Law is seen in almost all technological progression, you're going to hear about it a lot more. Probably about twice as much every year or so.
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Actually I learned Ohm's law in a high school computer/networking class. Never got around to taking physics.
Coles Law is my favorite.
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Moore pics please.
I think everyone understands Moore's law is not a law in the scientific sense, but rather a Coloquialism like "Murphy's law".
It also somewhat useful. It lets us make some basic assumptions like, ok I have W data today, the volume grows at rate X/year, it takes Y machines to handle that today, and based on Y doubling in capacity every 18 months or so I will need Z machines for the future state. Can I continue to scale like this?
Is it accurate, precise, or grounded in solid facts no but its still a nice rule of thumb permits some crude planning around a future with many unknowns.
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exponential growth
y=x(1+r)^t
where x is the starting value, r is the rate of growth (doubling = 100% = 1) and t is a discrete interval (1 = 18 months, 2 = 36 months, etc)
given a starting value of 1000, after 18 months, it doubles.
y = 1000(1+1)^1 = 1000(2) = 2000
after 36 months, it doubles again
y = 1000(1+1)^2 = 1000(4) = 4000
after 54 months, it doubles again
y = 1000(1+1)^3 = 1000(8) = 8000
after 72 months, it doubles again
y = 1000(1+1)^4 = 1000(16) = 16000
this is a straight out of the textbook definition of exponential growth. derp.
The wires are composed of doped silicon, and features of doped silicon are at least several atoms big. It may be made of bunch of atoms of dopants, but they are embebed on a crystal dozens of atoms wide. Also, the wires ccertanly an't work without those dozens of atoms, and another wire can't be as close to share some of those atoms without being connected. For all practical porposes, the wire is dozens of atoms wide.
Why can't /. just anounce a semiconductor breakthrough for what it is? "Smaler wire made of silicon" would make it, for exemple.
And, by the way, Ohm's law holds at the atomic level as well as it holds for big conductors. People learned that by studying organic conductors ages ago. The problem is how to make silicon work the same way. That is what TFA seems to be about (don't really know because it is behind a pay wall).
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It sounds like they've created nano-scale insulated wire, kinda like myelin-coated nerve fibers.
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A law in this usage of the word is neither a guideline nor a legality; it is an observed fact that is assumed to be true, like the 1st law of thermodynamics.
Isn't the first law of Thermodynamics that you don't talk about Thermodynamics?
+1 IDisagreeSoHeMustBeATrollOrAnAstroturferOrAShill
More like a "rule of thumb" then.
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Well, fair enough, but what about Slashdot?
no, it is just an approximation that is useful. Some materials have negative resistance, others complicated nonlinear functions. ohm's law is not universally true. Many other so-called "laws" are this way,Boyle's, Hooke's, Charle's., etc. Just useful approximations for some common cases with plenty of exceptions and even some things acting the opposite way.
The chart you referenced has a logarithmic y-axis; a 'straight' line in logarithmic space is not linear; it's exponential. Try plotting the same data with a linear y-axis.
Damn, my fault for not reading the axes and just getting a chubby over seeing the charts that matched what I was thinking. Thx everyone for the lesson.