When
electronic devices overheat, they can slow down, malfunction, or stop working
altogether. This heat is mainly caused by energy lost as electrons move through
a material—similar to friction in a moving machine.
Most devices today use silicon (Si) as
their semiconductor material. However, engineers are increasingly turning to
alternatives like gallium nitride (GaN) for longer lifetime use and higher
performance. This includes products such as LEDs, compact laptop chargers, and
5G phone networks.
For even more extreme applications—such
as high-voltage systems or harsh environments—researchers are exploring ultrawide bandgap (UWBG)
materials like gallium oxide (Ga2O3),
aluminum gallium nitride (AlGaN), and even diamond.
The key difference between these
materials lies in their electronic bandgap—the energy needed to get electrons
to flow through the material. Wider bandgaps allow companies to reduce the size
of their electronics and make them more electrically efficient.
"UWBG materials can resist up to
8,000 volts and can operate at temperatures over 200°C (392°F), making them
promising for the next generation of electronics in the energy, health, and
communication sectors," explains Georges Pavlidis, assistant professor of
mechanical engineering.
While these materials offer promising
advantages, they also come with challenges. They're currently expensive,
difficult to manufacture, and their thermal behavior is hard to measure
precisely. As electronics become more powerful and in smaller dimensions, the
heating in the device becomes more localized and can generate a heat flux greater than the sun, Pavlidis explains.
"Chip manufacturers need new
methods to measure temperature in smaller dimensions," he says.
Pavlidis, along with UConn's School of
Mechanical, Aerospace, and Manufacturing Engineering Ph.D. candidates Dominic
Myren and Francis Vásquez, collaborated with colleagues from the U.S. Naval
Research Laboratory over the past year to tackle the challenge of measuring the
heat output. Their work resulted in a "Perspectives" paper published in Applied
Physics Letters.
"A 'Perspectives' paper is intended
to be an outline of what's coming soon, get people excited about what's coming,
and encourage other researchers to start looking into similar topics,"
says Myren, a National Defense Science and Engineering Graduate Fellow who has
seven years of industrial R&D experience in fuel systems, internal
combustion, and engine controls and holds patents related to electromagnetic
actuators and engine controls.
"The push right now is for the
development of thermal management strategies in wide and ultra-wide bandgap
semiconductor devices. We have a lot of open questions, and we're working hard
on them over in Dr. Pavlidis' lab, but the cross-pollination of ideas is how
academic circles thrive."
In the article titled "Emerging
Thermal Metrology for Ultrawide Bandgap Semiconductor Devices," the
co-authors discuss the pros and cons of using UWBG material for semiconductors,
and outline several innovative techniques for measuring temperature at the
microscale. These methods could help engineers design faster, more powerful electronic devices—without the risk of overheating.
After
the paper ran online in late May, the co-authors received an unexpected note
from the editors at Applied Physics
Letters. "[We] felt that your article is noteworthy, and have chosen
it to be promoted as an Editor's Pick. It will be posted on the journal
homepage, and a badge will be displayed next to the title."
"It
is no small feat for a publication to be chosen as an Editor's Pick in the
highly regarded Applied Physics Letters that
publishes more than 2,000 articles a year," says JC Zhao, dean of the
UConn College of Engineering. "I congratulate Professor Pavlidis and his
group on this recognition and I am very proud of their accomplishment."
Vásquez's
particular research interests are thermal management for high-power and
radio-frequency (RF) power electronics. In Pavlidis's lab, he enjoys the
combination of research and meaningful application where the group solves real
challenges in electronics and photonics that directly impact energy efficiency,
reliability, and performance.
"What
makes the experience truly special is the lab culture," Vásquez says.
"Professor Pavlidis is incredibly supportive and patient, especially when
we hit difficult knowledge to explain, and he always encourages us to stay
curious.
"His
approach pushes us to explore new ideas, test them rigorously, and think about
how our work can translate into real-world innovations. It's that mix of
intellectual freedom and high standards to make an impact that keeps me excited
every day in the lab."
In
the paper, the researchers explore several options for measuring temperature in
UWBG devices. They suggest using optical methods like Raman spectroscopy
and thermoreflectance, which use light to measure temperature-dependent
properties. Electrical methods use electric signals to detect temperature, and
scanning probe methods, like scanning thermal microscopy, touch the surface to
feel the heat.
The
researchers also describe exciting new ideas, such as combining thermal images
created from different colors of light to see heat in nitride-based devices, or
measuring how light is absorbed in material defects to calculate the
temperature in gallium oxide electronics. They're even working on a new kind of
microscope that can see very tiny heat patterns using deep ultraviolet light.
"These
proposed methods provide a solution to measuring the peak temperature in future
electronics, which is the primary indicator of when the device will fail.
Providing the industry with accurate metrology will lower the barrier to
commercialization and enable engineers to develop new thermal management
strategies," Pavlidis says.
The
group's research is supported by Microelectronics Commons, a program
specifically created to commercialize UWBG devices for power electronics. The
Commons program established the Northeast Microelectronics Coalition Hub, a
network of more than 200 organizations, academic institutions, commercial and
defense companies, and federally-funded centers concentrated in eight northeast
states. The idea for the paper stemmed from a project Pavlidis worked on last
summer as an Office of Naval Research Fellow.
Moving
forward, Pavlidis—who was promoted to a Senior Member of Institute of
Electrical and Electronics Engineers (IEEE) this month—aims to work with
semiconductor partners in developing affordable strategies to reduce the
temperature in power electronics. By pushing the resolution limits of
temperature measurements, the lab plans to extend their methods to improve
other technologies such as quantum computing and photonic circuits.
They've
already worked with colleagues at the University of Maryland to design photonic
hardware for next-generation data storage. That study is published in Nature Communications.
"We hope our work has laid the foundation for the thermal design of the next generation of UWBG devices," Pavlidis says.
Source: Researchers outline innovative ways to track heat in advanced semiconductors
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