Tiny Transistors a Big Leap for Technology
Scientists announced Thursday the creation of transistors many times smaller than those found in today’s most advanced microprocessors, and which operate efficiently at room temperature.
This advance in nanotechnology was heralded as a critical step toward the eventual creation of microchips millions of times more powerful than today’s models, that one day will be the backbone of intelligent devices too tiny to be seen by the naked eye. Nanotechnology is an emerging science based on building molecular-scale machines atom by atom.
Some experts foresee a nanotech evolution within a couple of decades when today’s microchips will face extinction, to be replaced with nanochips that offer millions of times more computing power in a microscopic package.
Scientists at Delft University of Technology in the Netherlands, writing in the current issue of the journal Science, built a transistor from only a single molecule 1 nanometer wide--about 1/10,000 the thickness of a human hair. Such nanotechnology devices previously had been reliably created only in super-cooled environments.
The tiny device can be toggled on and off using a single electron. The experiment could eventually lead to vast power savings over today’s transistors, which require several hundred to millions of electrons to perform the same function. “It’s another significant obstacle which no longer stands in the way of implementing nano-scale technologies in real electronics,” said Don Eigler, an IBM fellow and a leading nanotechnology authority.
Transistors are the building blocks of today’s integrated circuits. Their ability to register an on or off state--”0” or “1” in the lingo of computer scientists--produces the basic structure of digital data. Millions of transistors operate in tandem within microprocessors to perform all manner of computations. The smaller the transistors, the more powerful the processor and the less energy required to operate it.
For decades, conventional microcircuits have been manufactured using photolithography, which uses light to etch circuits on a photosensitive film covering silicon chips. Technologists have continually refined this technique consistent with Moore’s Law. That precept, coined by Intel Corp. co-founder Gordon Moore in 1965, holds that every 18 to 24 months microprocessors become twice as fast as the size of transistors and chips shrinks.
But Moore’s Law may be running out of steam. “Within 10 years, [photolithography] will really encounter barriers--scientific and in terms of investment in new factories,” said Cees Dekker, a professor at Delft and chief author of the Science report. It has become increasingly difficult to shrink processors, and incremental gains may drive manufacturing costs to impractical levels.
However, many scientists believe nanotechnology can someday extend Moore’s Law.
Early computers took up a whole room to accommodate thousands of vacuum tubes used to process data. The invention of the integrated circuit in the late 1950s changed all that by compressing far more computing power into microprocessors loaded with solid-state transistors.
Nanotechnology is being researched by scientists in many parts of the world. The most optimistic researchers project the creation of super-intelligent, microscopic devices that will push computing into futuristic realms. A multitude of micro devices might solve the toxic waste problem by disassembling poisonous molecules, such as dioxin, into the innocuous atoms that compose them, for example.
Eric Drexler, a leading proponent of nanotechnology, has suggested that nanomachines will eventually be injected into cancer victims. The tiny robots would be programmed to recognize and kill malignant cells--much as an antibody can kill a disease-causing virus.
Less-sophisticated nanotech medical tools may emerge within a few years, suggests Phil Kuekes, a computer scientist at Hewlett-Packard Labs and an expert in molecular-scale processors.
Intelligent nano-scale devices could be injected as “biological sensors in the body, or for diagnostic purposes in the clinic,” Kuekes said. The probes could be powered by ambient light or body heat and deliver a constant stream of data about disease organisms or other medical conditions.
Other scientists remain skeptical, saying that the absence of enabling technologies--such as wireless communications and power supplies--make such advances unfeasible any time soon.
“Every scheme that I’ve ever heard of along those lines doesn’t make any physical sense to me,” Eigler said. He pointed out that just because H.G. Wells could imagine a time machine doesn’t mean that one can be created based on any actual scientific principles.
Eigler added: “I try to distinguish between the ‘what-ifs’ and the . . . things that are in the realm of the reasonable.”
Still, Dekker’s team brought the prospect of nano-scale processors slightly closer to reality. They created a single-electron transistor by bending a molecule known as a carbon nanotube--a hollow cylinder that resembles a drinking straw. Using an atomic force microscope--an instrument capable of moving individual atoms--researchers pushed on the tube, causing it to buckle in two places. Like a bent straw restricting the volume of water passing through it, the bent nanotube enables one electron to move through at a time.
“The next thing will be developing strategies to assemble such devices into processors--a chip that can do computations,” Dekker said.
But scientists do not yet know how to mass produce nano-scale transistors, or how to create wiring between them--both essential to creating nanochips. Conventional wiring, created using photolithography, would be too massive for nanocircuitry.
Kuekes believes that nano-scale circuitry will be created commercially within a few years using a chemical process. His solution is to “grow” linked transistors of the kind produced by Dekker in the way crystals are grown, from combinations of chemicals.
A true microprocessor based on such methods won’t be possible for at least a decade, Kuekes said.
But he speculates that within a few years single-purpose nanotechnology gadgets may be available. A credit-card-size device could hold many times as much computer data as today’s largest storage drives, for example. Such a device might easily secure backup of all the business records of a large corporation.
Skeptics contend that practical applications of nanotechnology are still a long way off. But a rush of incremental nanotech advances--such as the Delft University team’s transistor--make it clear that nanotechnology is moving out of the realm of science fiction.
