Researchers outline innovative ways to track heat in advanced semiconductors

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.