From: John K Clark (jonkc@att.net)
Date: Mon May 20 2002 - 13:35:43 MDT
>From today's New York Times
=======================
At I.B.M., a Tinier Transistor Outperforms Its Silicon Cousins
By BARNABY J. FEDER
IBM. researchers have created carbon nanotube transistors that
substantially outperform models of even advanced silicon devices without
departing from the most common design of silicon chips.
The I.B.M. transistors also have a higher capacity for carrying electrical
current - a measure related to transistor speed - than previously designs
using nanotubes.
Nanotubes are tube-shaped molecules of carbon 50,000 times as thin as a
human hair. Although commercial products are probably years away, the
research provides the strongest indicator yet that carbon nanotubes could be
feasible successors to today's silicon devices when developers reach the
point where it is impossible to improve microchips by shrinking silicon
designs further, according to Dr. Phaedon Avouris, manager of nanoscale
science at I.B.M. Research in Yorktown Heights, N.Y.
The research results are being reported today in the Journal of Applied
Physics Letters.
Compared with previous designs for nanotube transistors, the I.B.M. models
use a more conventional arrangement of the various elements of the
transistor, like insulators and the gate that switches current on or off,
found in conventional silicon chips. Such arrangements are thought to be
well suited to combining many transistors into logic circuits and low power
consumption.
I.B.M. said that the nanotube transistors it built also carried two to four
times as much current as comparable silicon devices. The devices are
commonly called Mosfets (for metal-oxide semiconductor field-effect
transistors).
Dr. Avouris said that the nanotube's performance relative to silicon should
improve as more is learned about how to build nanotube structures. In
addition, I.B.M. expects to achieve big gains in nanotube performance simply
by shrinking their dimensions. Right now, several important elements are
currently 10 times the size of their counterparts in the silicon models.
"There are some obvious ways of improving the nanotubes," said Dr. Avouris.
For all the progress, he said it would be two to three more years before
I.B.M. was ready to work on prototypes of future nanotube chips and as many
as 10 years before they would be commercially available.
"I don't think we'll see a sharp transition from silicon to nanotubes," said
Dr. Avouris. "We expect to move to hybrids first."
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