An international team of researchers have used a unique tool inserted into
an electron microscope to create a transistor that's 25,000 times smaller
than the width of a human hair.
The research, published in the journal Science, involves researchers from
Japan, China, Russia and Australia who have worked on the project that began
five years ago.
QUT Center for Materials Science co-director Professor Dmitri Golberg, who
led the research project, said the result was a "very interesting
fundamental discovery" which could lead a way for the future development of
tiny transistors for future generations of advanced computing devices.
"In this work, we have shown it is possible to control the electronic
properties of an individual carbon nanotube," Professor Golberg said.
The researchers created the tiny transistor by simultaneously applying a
force and low voltage which heated a carbon nanotube made up of few layers
until outer tube shells separate, leaving just a single-layer nanotube.
The heat and strain then changed the "chilarity" of the nanotube, meaning
the pattern in which the carbon atoms joined together to form the
single-atomic layer of the nanotube wall was rearranged.
The result of the new structure connecting the carbon atoms was that the
nanotube was transformed into a transistor.
Professor Golberg's team members from the National University of Science and
Technology in Moscow created a theory explaining the changes in the atomic
structure and properties observed in the transistor.
Lead author Dr. Dai-Ming Tang, from the International Center for Materials
Nanoarchitectonics in Japan, said the research had demonstrated the ability
to manipulate the molecular properties of the nanotube to fabricated
nanoscale electrical device.
Dr. Tang began working on the project five years ago when Professor Golberg
headed up the research group at this center.
"Semiconducting carbon nanotubes are promising for fabricating
energy-efficient nanotransistors to build beyond-silicon microprocessors,"
Dr. Tang said.
"However, it remains a great challenge to control the chirality of
individual carbon nanotubes, which uniquely determines the atomic geometry
and electronic structure.
"In this work, we designed and fabricated carbon nanotube intramolecular
transistors by altering the local chirality of a metallic nanotube segment
by heating and mechanical strain."
Professor Golberg said the research in demonstrating the fundamental science
in creating the tiny transistor was a promising step towards building
beyond-silicon microprocessors.
Transistors, which are used to switch and amplify electronic signals, are
often called the "building blocks" of all electronic devices, including
computers. For example, Apple says the chip which powers the future iPhones
contains 15 billion transistors.
The computer industry has been focused on developing smaller and smaller
transistors for decades, but faces the limitations of silicon.
In recent years, researchers have made significant steps in developing
nanotransistors, which are so small that millions of them could fit onto the
head of a pin.
"Miniaturization of transistors down to nanometer scale is a great challenge
of the modern semiconducting industry and nanotechnology," Professor Golberg
said.
"The present discovery, although not practical for a mass-production of tiny
transistors, shows a novel fabrication principle and opens up a new horizon
of using thermomechanical treatments of nanotubes for obtaining the smallest
transistors with desired characteristics."
Reference:
Dai-Ming Tang et al, Semiconductor nanochannels in metallic carbon nanotubes
by thermomechanical chirality alteration, Science (2021).
DOI: 10.1126/science.abi8884