The blog of Xeno, a slightly mad scientist
… This image from a computational simulation run of the wires shows electron density as electrons flow from left to right. The wires are 20 times smaller than the smallest wires now available and measure just four atoms wide by one phosphorus atom tall. (Purdue University image/Sunhee Lee, Hoon Ryu and Gerhard Klimeck)
The smallest wires ever developed in silicon – just one atom tall and four atoms wide – have been shown by a team of researchers from the University of New South Wales, Melbourne University and Purdue University to have the same current-carrying capability as copper wires.
Experiments and atom-by-atom supercomputer models of the wires have found that the wires maintain a low capacity for resistance despite being more than 20 times thinner than conventional copper wires in microprocessors.
The discovery, which was published in this week’s journal Science, has several implications, including:
* For engineers it could provide a roadmap to future nanoscale computational devices where atomic sizes are at the end of Moore’s law. The theory shows that a single dense row of phosphorus atoms embedded in silicon will be the ultimate limit of downscaling.
* For computer scientists, it places donor-atom based silicon quantum computing closer to realization.
* And for physicists, the results show that Ohm’s Law, which demonstrates the relationship between electrical current, resistance and voltage, continues to apply all the way down to an atomic-scale wire.
Bent Weber, the paper’s lead author and a graduate student in the Centre of Excellence for Quantum Computation and Communication Technology at the University of New South Wales, was thrilled with the finding.
“It’s extraordinary to show that Ohm’s Law, such a basic law, still holds even when constructing a wire from the fundamental building blocks of nature – atoms,” he says.
The innovation of the Australian group was to build the circuits up atom by atom, instead of the current method of building microprocessors, in which material is stripped away, says Gerhard Klimeck, a Purdue professor of electrical and computer engineering and director of the Network for Computational Nanotechnology.