Date: September 10, 2014
Source: University of Texas at Arlington
Summary: A team of researchers has discovered
a way to cool electrons to minus 228 degrees Celsius without external means and
at room temperature, an advancement that could enable electronic devices to
function with very little energy.
A team of researchers has discovered
a way to cool electrons to -228 °C without external means and at room
temperature, an advancement that could enable electronic devices to function
with very little energy.
A chip, which contains nanoscale
structures that enable electron cooling at room temperature, is pictured. The
process involves passing electrons through a quantum well to cool them and keep
them from heating. The team details its research in "Energy-filtered cold
electron transport at room temperature," which is published in Nature
Communications on Wednesday, Sept. 10.
"We are the first to
effectively cool electrons at room temperature. Researchers have done electron
cooling before, but only when the entire device is immersed into an extremely
cold cooling bath," said Seong Jin Koh, an associate professor at UT
Arlington in the Materials Science & Engineering Department, who has led
the research. "Obtaining cold electrons at room temperature has enormous
technical benefits. For example, the requirement of using liquid helium or
liquid nitrogen for cooling electrons in various electron systems can be
lifted."
Electrons are thermally excited even
at room temperature, which is a natural phenomenon. If that electron excitation
could be suppressed, then the temperature of those electrons could be
effectively lowered without external cooling, Koh said. The team used a nanoscale structure
-- which consists of a sequential array of a source electrode, a quantum well,
a tunneling barrier, a quantum dot, another tunneling barrier, and a drain
electrode -- to suppress electron excitation and to make electrons cold.
Cold electrons promise a new type of
transistor that can operate at extremely low-energy consumption.
"Implementing our findings to fabricating energy-efficient transistors is
currently under way," Koh added.
Khosrow Behbehani, dean of the UT
Arlington College of Engineering, said this research is representative of the
University's role in fostering innovations that benefit the society, such as
creating energy-efficient green technologies for current and future
generations.
"Dr. Koh and his research team
are developing real-world solutions to a critical global challenge of utilizing
the energy efficiently and developing energy-efficient electronic technology
that will benefit us all every day," Behbehani said. "We applaud Dr.
Koh for the results of this research and look forward to future innovations he
will lead." Usha Varshney, program director in
the National Science Foundation's Directorate for Engineering, which funded the
research, said the research findings could be vast. "When implemented in
transistors, these research findings could potentially reduce energy
consumption of electronic devices by more than 10 times compared to the present
technology," Varshney said. "Personal electronic devices such as
smart phones, iPads, etc., can last much longer before recharging."
In addition to potential commercial
applications, there are many military uses for the technology. Batteries weigh
a lot, and less power consumption means reducing the battery weight of
electronic equipment that soldiers are carrying, which will enhance their
combat capability. Other potential military applications include electronics
for remote sensors, unmanned aerial vehicles and high-capacity computing in
remote operations.
Future research could include
identifying key elements that will allow electrons to be cooled even further.
The most important challenge of this future research is to keep the electron
from gaining energy as it travels across device components. This would require
research into how energy-gaining pathways could be effectively blocked.
Co-authors of the paper are Pradeep
Bhadrachalam, Ramkumar Subramanian, Vishva Ray and Liang-Chieh Ma from UT
Arlington, and Weichao Wang, Prof. Jiyoung Kim and Prof. Kyeongjae Cho from UT
Dallas who also were part of the research team.
Story Source:
The above story is based on materials provided by University
of Texas at Arlington. Note: Materials may be edited for
content and length.
Journal Reference:
1.
Pradeep Bhadrachalam, Ramkumar
Subramanian, Vishva Ray, Liang-Chieh Ma, Weichao Wang, Jiyoung Kim, Kyeongjae
Cho, Seong Jin Koh. Energy-filtered cold electron transport at room
temperature. Nature Communications, 2014; 5: 4745 DOI: 10.1038/ncomms5745
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