Carbon Nanotubes & Plastic Transistors
- What does this mean for the future of better motors & better batteries?
(Excerpt... much more where those came from... RC)
PC Magazine :: July 2003
Materials: Carbon Nanotubes
By Cade Metz
It's the Clark Kent of microelectronics. In the early 1990s, scientists at
the NEC Fundamental Research Laboratory in Tsukuba, Japan, discovered a tiny
graphitelike structure with the most beguiling dual identity. Sometimes it's
a metal, and sometimes it's a semiconductor. It can serve as a wire,
transporting current from one place to another, and it can also serve as a
transistor, using changes in current to store information.
This microscopic structure, known as a carbon nanotube, could be the secret
to extending Moore's Law-which predicts that the number of transistors on
the fastest CPUs will double every 18 months-beyond the limits of today's
silicon microprocessors (quite a feat in itself). "This is our best hope for
the next generation of electronics," says Jie Liu, a Duke University chemist
at the forefront of carbon nanotube research. It is also the basic building
block for all sorts of future products, from flat-panel displays and
long-lasting batteries to fishing poles and satellite cables (pound for
pound, nanotubes are 10 to 100 times as strong as steel).
AMD, IBM, and Intel will continue to improve silicon-based CPUs for at least
another decade (see "Extreme Ultraviolet Lithography" below). But when they
are unable to shrink silicon transistors any further, they may abandon
silicon altogether and move on to completely new materials.
Only 1/100,000 the thickness of a human hair yet exceedingly durable, a
carbon nanotube is akin to graphite-a sheet of carbon atoms arranged in a
tight honeycomb pattern. Your pencil tip consists of stack after stack of
such microscopic sheets. Carbon nanotubes are formed when the sheets of
atoms are rolled into cylinders. "They look a lot like hollow cigars," says
IBM researcher Joerg Appenzeller.
When carbon atoms assume a certain arrangement along the length of a tube,
the nanotube behaves like a semiconductor. In a different arrangement, it
becomes a metal. Semiconductors conduct current at certain voltages but not
others. They are used to build transistors, in which processors store
information. When one voltage is applied, current flows freely through the
nanotube, and the transistor turns on. When a different voltage is applied,
the current stops, and the transistor turns off. Metals, which conduct at
any voltage, are used to build the wires that connect transistors.
In theory, you could build an entire microprocessor from carbon nanotubes.
Its parts would be far smaller-and thus far faster-than the copper wires and
silicon transistors used today.
Nanotubes are the by-products of various chemical reactions. Scientists can
easily grow them on a substrate by reproducing these reactions, but they're
struggling to arrange nanotubes in complex circuit patterns.
Researchers are still seeking answers. "How do you control their physical
properties? How do you grow them in the right place? How do you connect
them?" asks Bob Gassar, director of components research at Intel. "Those are
not trivial problems, and they may never be solved."
Carbon nanotubes show promise for an extraordinary variety of products. IBM
recently demonstrated a carbon nanotube that produces infrared light.
Motorola and Samsung are working on carbon nanotubes for flat-panel
displays. Nantero is developing nanotube-based memory. And researchers at
the University of North Carolina have shown carbon nanotube batteries to
hold twice as much energy as conventional batteries.
Intel has just launched a research program on carbon nanotubes, which means
the company believes there's a good chance they'll be used in
production-level processors within the next ten years. A dual identity has
Microprocessors: Extreme Ultraviolet Lithography
By Cade Metz
The future of Moore's Law is all smoke and mirrors. Companies like AMD, IBM,
and Intel will continue using silicon to build smaller and faster
microprocessors for at least another ten years, but not without the help of
extreme ultraviolet (EUV) lithography, a new way of printing circuit
patterns onto silicon that eschews lasers and lenses in favor of xenon gas
and microscopic reflectors.
Tried-and-true optical lithography techniques that print patterns with
features as narrow as 65 nanometers will extend Moore's Law into 2007. Only
EUV can stretch it into the next decade, shaving feature widths to 32
When Moore made his seminal prediction in 1965, microprocessors were built
with essentially the same optical lithography techniques used today, which
rely on lasers and lenses to print circuit patterns onto silicon wafers. A
laser shines ultraviolet light onto a mask-a tiny cutout of the pattern
being printed-and as the light shines through the mask, it conforms to the
pattern. Tiny glass lenses then reduce its wavelength.
To build smaller and smaller circuits, manufacturers have improved the
precision of the laser and lenses, reducing the wavelength of the light
hitting the wafer. Equipment used to build the Intel Pentium 4 and the AMD
Athlon produces an ultraviolet light with a wavelength of 248 nm, printing
circuit patterns with features around 130 nm wide. Later this year, Intel
will move to a 193-nm optical system.
But optical lithography will soon reach its limit. "You run into severe
materials problems when you drop below 193-nm wavelengths," says Gregg
Gallatin, an IBM researcher. In order to develop a 157-nm optical system,
which will debut in 2007, scientists had to construct lenses from entirely
new materials. Glass wouldn't work. "When you get down to 157 nm, you have
to use a single-crystal material called calcium fluoride," says Gallatin.
"And it was a lot harder and took a lot longer to grow calcium fluoride with
the required optical quality than people expected." Building lasers and
lenses capable of wavelengths below 157 nm proved impossible.
Researchers sought out alternative forms of lithography, eventually settling
on EUV. Rather than using a laser as a light source, an EUV system produces
ultraviolet light by electrically exciting xenon gas. To hone the light, it
uses specialized mirrors instead of lenses. By reflecting the light off
these microscopic mirrors, the system narrows wavelengths to about 13 nm.
The EUV LLC Consortium, an Intel-led group that includes AMD, IBM, Infineon,
Micron Technology, and Motorola, hopes to debut EUV around 2009, shrinking
CPU feature widths to around 32 nm. But the technology needs fine-tuning.
"It's still not clear that this will be a cost-effective solution," says
Gallatin. "EUV has the technical capability, but it may cost a horrendous
amount of money to put into production."
Intel Fellow Peter Silverman is confident that the technology will launch as
scheduled. "EUV will be affordable for leading-edge companies," he says.
"You don't need a lot of tools for the first generation, and there's time to
get the cost down for the second generation." Chances are, Moore's Law will
reach its golden anniversary.
Materials: Plastic Transistors
By Cade Metz
That famous line from The Graduate isn't as ridiculous as it once was.
Today, plastics are the future of the $30 billion computer display market,
and they may even lead to new breeds of computer memory and microprocessors.
Within five years, companies like DuPont and Xerox will begin using
plastics, in conjunction with organic light-emitting diode technology (see
"OLED Displays" below) and organic transistors, to build flexible displays.
Eventually, plastics could be used to build entire machines that you can
bend and drop without breaking. "These devices will be so flexible and light
that we'll be able to integrate them directly onto almost any type of matter
we want, including a piece of clothing," says Beng Ong, a research fellow
and manager of the printed organic electronics group at the Xerox Research
Centre in Mississauga, Ontario.
Silicon transistors-the engines of microprocessors, displays, and memory
modules-are fast and effective, but manufacturers must build them on flat,
rigid materials. The extreme heat required to etch circuits in silicon would
melt any sort of flexible material. That's why you never see curved LCDs,
and you can't twist your laptop. Recently, scientists at Bell Labs and Xerox
have found ways of using organic materials rather than silicon to build
electronics. Such materials can be manipulated at room temperature, which
would let manufacturers build devices on flexible plastic.
One well-known example is the OLED, but researchers have also found ways of
fashioning full-fledged transistors from organic materials. Like OLEDs,
organic transistors could be used in plastic displays within five years and
in electronic paper within a decade. If scientists can make them fast
enough, plastic memory and microprocessors could be next.
Such plastic devices will not only be supple, they'll be resilient. "You
won't have to worry about dropping your Palm Pilot or sitting on it," says
Cherie Kagan, an IBM researcher who's worked on plastic electronics for the
past five years. And they may be even cheaper than silicon-based devices.
Manufacturing silicon requires not only high temperatures but also
clean-room and vacuum environments. Scientists hope to manufacture plastic
devices easily under ordinary conditions. In December, Ong and his team of
Xerox scientists announced that they had produced an organic transistor that
retains its performance even when exposed to oxygen.
Eventually, plastics will enable true wearable computing: Not only displays
but entire systems could one day be woven into our clothes. Are you
listening, Benjamin Braddock?
Materials: OLED Displays
By Carol Levin
When Kodak researcher Ching Tang noticed a green glow from some organic
material he was experimenting with at his lab in 1985, he discovered
something big. He had just invented an organic light-emitting diode (OLED),
launching an industry expected to reach over $3 billion by the end of this
Simply put, an OLED uses a carbon-based designer molecule that emits light
when an electric current passes through it. Piece lots of molecules together
and you've got a superthin display of stunning quality-no power-draining
backlight required. Conveniently, OLED displays can be produced in the same
way an ink jet printer sprays ink onto a sheet of paper, making
manufacturing cheap and simple.
But here's the real clincher: OLEDs can be printed onto flexible plastic.
Sheets of them could be easily produced, opening a new universe for product
designers, from displays that roll up to ones that are woven onto clothing.
(See "Plastic Transistors".)
In anticipation of this future, a flurry of business and scientific activity
is under way. The technology is being perfected (blue emitters in particular
are stubborn), and OLED intellectual property is hotter than ever. "Every
major player is a licensee of Kodak or Cambridge Display Technology," says
Kimberly Allen, director of technology and strategic research at
Given the endless possibilities of plastic displays, DuPont-Kodak's primary
competitor-recently launched its DuPont Displays division and its Olight
brand to bring OLEDs to the people the way it has brought Lycra and Teflon.
And it's working closely with Universal Display Corp., a major patent
In partnership with RiTdisplay Corp., DuPont has a giant production facility
in Hsinchu, Taiwan, that's already turning out OLED displays. Ultimately,
DuPont expects to use roll-to-roll manufacturing to create plastic displays
by the mile.
OLEDs have distinct advantages over existing LCD flat panels in brightness,
power efficiency (10:1 by some estimates), viewing angle, and refresh rate
(making them great for video). And they've come a long way since the 1980s,
when the glow from an OLED would fade after 10 minutes. Scientists are still
working to make OLEDs even more energy-efficient so they don't drain
notebook and PDA batteries.
But products are the ultimate goal. OLEDs will show up initially in cell
phones and digital cameras; the new Kodak EasyShare LS633 has one. And once
manufacturing yields improve (around 2005), they'll appear in glass
flat-panel displays. Sony already has a prototype 10-inch notebook display
(see the Prototype Gallery on this page), but volume shipments won't start
until 2009. The transition to plastic displays is three to five years out.
And with some patience, we'll eventually see those roll-up displays.
In the near term, the challenge is getting a deep-blue emitter. "We're
closing in on that rapidly," says Dalen Keys, chief technology officer for
DuPont Displays. There's nothing like a little healthy competition to
Broadband: Silicon Photonics
By Davis D. Janowski
Chuck Yeager broke the sound barrier in October 1947, and soon after,
everyone wanted to fly fast. But it was almost another decade before
commercial jet traffic really took off. Then jetliners weren't fast enough,
and the race to construct supersonic airliners began. The problem was-and
still is-that no one could make an airline based on supersonic travel
Our relationship with the Internet is much the same. The backbone-the fat,
fiber-optic pipes that form a mesh of light-wave traffic connecting almost
every metropolitan network worldwide-is plenty fast enough and has bandwidth
to spare, yet we all clamor for faster connections. We are actually
hankering for faster connections between our homes and that speedy
backbone-a distance known as the last mile. But getting there has been
One of many technologies poised to make super-high-speed Internet access as
well as voice and video services a reality is silicon photonics. Chips built
with it would carry light-based traffic rather than electronic traffic-and
photons are faster than electrons.
Today, a handful of new home developments around the country have
fiber-optic lines installed underground, supplying each home with a 40-Mbps
pipe for an Internet connection, streaming audio and video, and Voice over
IP services. That blows away cable's 1.5-Mbps top speed.
But such systems are expensive and bulky, taking up space in the central
office (CO). That's where the all-optical Internet backbone ends for most
folks. COs are windowless cinder-block buildings, often just off the beaten
path, that house banks of analog and digital voice switches. But the COs
don't have space for the new equipment from manufacturers like Alcatel and
Cisco Systems, and phone companies don't have the resources to drive
Before high-speed links emerge on a wide scale, manufacturers need to
miniaturize the equipment and reduce the costs of the optical-or more often,
hybrid optoelectrical-hardware. That's where integrated
photonics-specifically the integrated optical circuit (IOC)-comes in. An IOC
is a chip with a light source, optical filters, photodetectors, and optical
Companies such as Avanex, Cidra Corp., NeoPhotonics, and others are vying to
bring IOCs to market, but the scientific challenges loom large. "The problem
with integrated photonics right now is that we are about where we were in
the 1940s with the integrated circuit," explains Kumar N. Sivarajan, CEO of
Tejas Networks. "We need a few key breakthroughs that would do for
integrated photonics what the transistor did for integrated circuits and
While the payoff could ultimately be substantial, it all really depends on
the economy. The companies most heavily involved in R & D-generally smaller
businesses that sell to the giants-are in a fragile fiscal state. "Right now
there's just not a lot of demand. It will take those folks farther up the
food chain to recognize a market materializing among providers and carriers
for delivering services," says Marlene Bourne, a senior analyst for research
Perhaps some help from the economy could quicken the pace and bring the
extraordinary potential of silicon photonics right to our doorsteps-sooner
rather than later.
Components: Magnetic Memory
By Cade Metz
It's happened more times than you care to remember. You're sitting at your
PC, putting the final period on that four-page e-mail, and your foot catches
the system's power cord, yanking it from the socket. The e-mail is lost
forever, and before you can start retyping it, you have to wait several
minutes for the machine to boot, cursing yourself as Windows lets out that
Such horror stories could soon be a thing of the past, thanks to
magnetoresistive random access memory, or MRAM for short. By the middle of
the decade, manufacturers expect to start building PCs with MRAM. If an MRAM
computer loses power, you can restart it in an instant, and when you do,
that four-page e-mail will be right where you left it.
Today's PCs use SRAM (static RAM) and DRAM (dynamic RAM), both known as
volatile memory. They can store information only if they have power. DRAM is
a series of capacitors that store information as electrical charges. A
charged capacitor represents a 1, and an uncharged capacitor represents a 0.
To retain a 1, you must constantly feed the capacitor with power. "The
charges you put into a capacitor are constantly leaking out," says Chia-Ling
Chien, a professor of physics in the Krieger School of Arts and Sciences at
Johns Hopkins University, whose research has long focused on magnetic
structures. "Several thousand times a second, you have to replenish them, or
they go away."
That's why when you pull the plug on your PC, everything stored in memory
vanishes. Work that hasn't been saved to your hard drive can never be
retrieved. And when you turn the system back on, it has to reload the entire
Gestating in research labs for decades, MRAM stores bits as magnetic
polarities rather than electrical charges. MRAM bits are made from
magnetized metal material. When a bit's polarity points in one direction, it
holds a 1. When its polarity points in another direction, it holds a 0. The
bits need electricity to change polarities but not to maintain them. MRAM is
nonvolatile, so when you turn off the power, all the bits retain their 1's
"If MRAM replaces DRAM, then you don't have to worry when your computer
crashes and you haven't saved what you're working on to your hard drive,"
says Chien. "Everything stays in memory." And you don't have to reload the
operating system, which stays in memory, letting you restart your system
MRAM will probably debut around 2004. In June 2002, Motorola demonstrated
the first 1-megabit MRAM chip. Hewlett-Packard and IBM are also working on
the technology. But it could be a while before MRAM is in every PC, because
manufacturers are set up to build DRAM, and replacing the infrastructure
takes time and money. "Any time you move away from pure silicon, there are
going to be problems that are very difficult to get past," says Jim Handy,
an analyst with market research firm Semico Research. He says MRAM won't
replace DRAM for another 10 to 20 years.
MRAM could let developers reinvent other parts of a PC as well. Potentially
much faster than the continuous magnetic media inside today's hard drives,
it may lead to better mass storage devices. And it may be the catalyst for a
new breed of microprocessor that PC manufacturers can customize. "Today,
every AND gate, every OR gate, is burned onto a processor and can't be
changed," says Chien, referring to a chip's logic architecture. "The hope is
that MRAM will one day be mature enough for programmable logic, so you could
build two identical chips and later reconfigure them to do completely
But that's just icing on the cake. The real news is that you won't have to
worry about your feet catching that power cord.
Recycling: Reverse Engineering
By Alan Cohen
We're good at recycling old soda cans, but when it comes to old PCs, our
work is cut out for us. Over the next three years, 250 million computers are
expected to become obsolete, according to the Environmental Protection
Agency. That's good news for PC manufacturers but bad news for the
environment. The problem: Old PCs can quickly become harmful PCs. A typical
computer monitor, for example, contains between 2 and 4 pounds of lead,
which can leach into the groundwater in a landfill.
The technology to recycle PCs exists. Facilities in Ohio and Pennsylvania
can reprocess the lead-laden glass in old computer monitors into glass for
new monitors. Metal can be extracted from old chips, and plastics can be
reused. Often, however, there is little incentive to do any of this.
Consumers balk at the cost of shipping junked systems to recycling
facilities. Manufacturers balk at taking on the responsibility of disposing
of systems they sold years ago (something manufacturers in Europe and Japan
already have to do). It's no surprise then that 85 percent of the 63 million
computers taken out of service in the U.S. last year wound up in landfills,
according to the National Safety Council.
The challenge isn't so much how to recycle PCs but how to make PC recycling
economically viable. It's a challenge that a team of researchers at the
Georgia Institute of Technology has taken up. "If we can figure out a way to
plan these systems so that they are economically sound, they will happen,"
says Jane Ammons, Georgia Tech's professor of industrial and systems
engineering, who runs the project along with Matthew Realff, associate
professor of chemical engineering.
The goal of the Georgia Tech project is to home in on optimal reverse
production systems-recycling infrastructures that reclaim as much of a used
device as possible at the lowest cost possible. The team has developed
mathematical models that evaluate existing recycling facilities, including
collection centers, glass-reprocessing plants, and smelting facilities. Such
models will determine the most efficient ways to use the facilities and help
researchers figure out the right combination of collection fees, tax breaks,
and additional reprocessing facilities.
Mathematical models have long been used to simulate systems, from airfoil
designs to presidential elections, but the difficulty in simulating
recycling is that the data is extremely uncertain. How many people will
participate in recycling? How many of the computers will be resalable? How
will participation be affected by recycling fees?
Ammons and Realff have a range of answers, extrapolated from surveys and the
experiences of the limited collection and recycling programs already under
way. Analyzing all the possible what-ifs requires some heavy-duty math and
major CPU time.
Within the next year, the team hopes to show the Georgia legislature some
recycling options-whether the state should impose a landfill ban or a
disposal fee, make collections mandatory, or encourage the opening of local
glass-reprocessing facilities. The ultimate goal is to make the system
available for any state or entrepreneur interested in setting up a recycling
program. Such a system should be available within five years.
By then the computers that made it possible will be ready for the junkyard
themselves. With a little luck-and a lot of math-they'll never get there.
Copyright (c) 2004 Ziff Davis Media Inc. All Rights Reserved.