## Ohm's Law Survives To the Atomic Level 104

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?'"*
## Re:Make your mind up! (Score:5, Informative)

They're different laws about different things, they just happen to relate in this instance.

## Let's be precise here,.. (Score:5, Informative)

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.

## Re:Encased in silicon crystal (Score:5, Informative)

## Re:Just a rant (Score:2, Informative)

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.