What it looks like
A single crossbar latch consists of a three wires: a "latch" wire and two control, or clock, wires. The latch wire lies under the other two. The wires are connected by molecules, which transfer electrical impulses from one wire to the next. (In the latches used to perform calculations, it is a layer of a common acid made up of carbon, hydrogen and oxygen.)
In layman's terms, a series of electrical impulses will close the molecular switch between the latch wire and the first clock wire. The impulses will then open the switch between the latch wire and other clock wire. In digital terms, a computer interprets this action as a "0". Conversely, opening the first switch and closing the second becomes a "1."
Earlier, Kuekes had produced crossbar latches that could perform basic calculations, but they couldn't store partial results for later usage. The new crossbar latches, however, detailed in an article in the Journal of Applied Physics, can: They conceivably perform transistor-like functions.
A key attribute of the switches is that the junction between the wires can be as small as 2nm. The equivalent junction in current transistors inside 90nm chips is about 60nm, meaning that far more crossbar latches can be put into the same space that now holds transistors. Traditional transistors, in fact, will never be able to hit these limits, Kuekes said.
"The three most important things are size, size and size," he said. "When you get down to around 15nm, the physics of semiconductor transistors will not work."
Shrinking the electrical junctions in a chip also generally increases performance, but the switches in the experimental crossbar latches only flip at about a tenth of a second.
Just as important, chips made on crossbar latches could be cheap to manufacture. The wires are put into place through nano-imprint lithography. In this technique, a customised mould is placed into a film later; the imprints left by the mould become the templates for the wires.
The molecular switches, meanwhile, do not have to be placed individually at the juncture of the wires. Only wires at the junctions will carry a current.
"Essentially, all of the other molecules are sacrificed," Williams said.
