Includes innovations to extend the performance of today’s silicon-based transistors, and new types of nano-electronic devices to complement and replace conventional technology in future computers

During the international IEDM 2016 conference, Purdue
University researchers showcased a range of concepts and technologies that
foreshadow the future of the semiconductor industry. The concepts included
innovations to extend the performance of today’s silicon-based transistors, and
new types of nano-electronic devices to complement and replace conventional
technology in future computers. 


Image source: Purdue University.

to professor of electrical and computer engineering and
director of Purdue’s Network for Computational Nanotechnology, Gerhard Klimeck,
electronic device innovation has been a major economic factor in the U.S. and
world economy. “These advancements were enabled by making the basic
transistors in computer chips ever smaller,” Klimeck said. “Today the critical
dimensions in these devices are just some 60 atoms thick, and further device
size reductions will certainly stop at small atomic dimensions.”

Of course, new technologies
will be needed for the industry to keep pace with Moore’s law, an observation
that the number of transistors on a computer chip doubles nearly every two
years, resulting in rapid progress in computers and telecommunications. It’s
becoming increasingly difficult to continue shrinking electronic devices made
of conventional silicon-based semiconductors, according to professor of electrical
and computer engineering, Muhammad Ashraful Alam.

Integrated circuits, also
known as chips, currently contain around two billion transistors. The more
devices that are packed onto a chip, the greater the heating. Today’s chips generate
about 100 watts per square centimeter, comparable to that of a nuclear reactor.

“As a result, self-heating has become a fundamental
concern that hinders performance and can damage transistors, and we are making
advances to address it,” Alam said.

Two of the five papers presented by Purdue at IEDM detail
research to suppress self-heating and enhance the performance of conventional
CMOS chips. The other papers deal with new devices for future computer
technologies that require lower power to operate, meaning they would not
self-heat as significantly.

“We are not only working to extend the state-of-art of
traditional technology, but also to develop next-generation transistor
technologies,” Alam said.

Transistors are electronic switches that turn on and off to
allow computations using the binary code of ones and zeros. A critical
component in transistors, called the gate, controls this switching. But, as
progressively smaller transistors are designed, this control becomes
increasingly difficult because electrons leak around the ultra-small gate.

One of the conference papers prepared by the researchers
focuses on a potential solution to this leakage: creating transistors that are
surrounded by the gate, instead of a customary flat design. But unfortunately,
surrounding the transistor with a gate causes increased heating, hindering
reliability and damaging the device. The researchers used a technique called submicron
thermo-reflectance imaging to pinpoint locations of excessive heating. Another
paper describes a potential approach to suppress this self-heating, modeling
how to effectively dissipate heat by changing how the transistor connects to
the complex circuitry in the chip.

As for the three remaining
papers, they propose next-generation devices: networks of nano-magnets, thin
layers of a material called black phosphorous, and “tunnel” field effect transistors,
or FETs. Technologies such as these would operate at far lower voltages than
existing electronics, generating less heat. The tunnel FETS could
potentially reduce power consumption by more than 40 times.

One of the conference papers
details research to develop devices made of black phosphorous, which may one
day replace silicon as a semiconductor in transistors. According to the
team, future research will include efforts to create smaller black phosphorous

A fifth paper describes how
networks of nano-magnets could serve as the building blocks of future computers.
The networks mimic Ising networks — named
after German physicist Ernst Ising — which
harness mathematics to solve complex problems.


Source: Purdue University,