Life on Earth could have evolved from silicon—the same as
today's microchips—but natural selection instead evolved carbon-based life. Now
human engineers are realizing that the same principles that enabled life to
emerge from carbon compounds could also solve the problems facing future
electronics.
IBM Research recently
created the world’s fastest carbon transistor (top) fabricated on the
industry’s first graphene wafers (bottom).
Today, the single most serious problem facing future
silicon-based electronics is excess heat generation. The smaller you make
silicon chips, the faster they go, but unfortunately they also generate more
heat. Carbon electronics, on the other hand, do just the opposite—that is, they
run cooler the smaller you make them. For instance, the human brain is more
powerful than the world's fastest supercomputer, and yet only consumes a mere
25 watts.
One area where silicon chips have already overheated and run
out of steam is radio frequency (RF) communications. Silicon chips today cannot
run much faster than 5GHz without generating enough power to melt themselves
down. Unfortunately, RF frequencies for future communications devices need to
run at up to 1,000GHz (1 terahertz).
The answer, according to the U.S. Defense Department, is
switching to carbon-based electronics. The Defense Advanced Research Projects Agency
(DARPA) recently tasked Program Manager Mike Fritz with the job of perfecting
carbon electronics for RF applications in its Carbon Electronics for RF
Applications (CERA) program. CERA funded IBM
Research efforts that recently passed a significant milestone along that road
by fabricating the world's fastest carbon transistor at 100GHz—more than 20 times
faster than the silicon CMOS (complementary
metal-oxide semiconductors) transistors used today.
"The 100GHz cutoff frequency recently demonstrated by
the IBM team in the CERA program is an
exciting milestone," says Fritz.
The first goal of CERA was to perfect a method of laying
down pure crystalline sheets of carbon on wafers, the same way that silicon is
layered in pure crystalline sheets from which CMOS
microchips are made. These carbon sheets are called graphene, and are currently
being fabricated onto wafers using the same techniques used to process silicon
wafers, albeit at smaller sizes today.
"In addition to pushing the speed metrics, the CERA program
will also continue to improve the wafer-scale graphene film quality,"
Fritz states. "The biggest challenge is achieving high-quality wafer-scale
synthesis of thin graphene films."
IBM Research recently reported progress in fabricating
these graphene films onto 2-inch wafers, from which it created its world's
fastest carbon transistor. There is still a long way to go—silicon chips are
made on much larger 12-inch wafers—but CERA is only just concluding the first
of three phases, each 18 to 24 months long.
