Researchers outline innovative ways to track heat in advanced semiconductors

If an electronic device overheats, it can slow down, malfunction, or stop operating completely. This heat is primarily caused by energy lost as electrons move through the material. This is similar to the friction of a moving machine.

Today, most devices use silicon (SI) as a 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 and harsh environments, researchers are exploring ultra-wave bandgap (UWBG) materials such as gallium oxide (Ga2O3), aluminum nitride (Algan), and even diamonds.

The important difference between these materials lies in the electronic bandgap. This is the energy required to flow electrons through the material. The wider bandgap allows businesses to reduce the size of their electronic devices and make them electrically efficient.

“UWBG materials can resist up to 8,000 volts and operate at temperatures above 200°C (392°F), making them promising for next-generation electronics in the energy, health and communications sectors,” explains Georges Pavlidis, assistant professor of mechanical engineering.

These materials offer promising benefits, but also come with challenges. Currently they are expensive, difficult to manufacture, and their thermal behavior is difficult to accurately measure. As electronics become more powerful and smaller in size, heating within the device becomes more localized and can produce heat fluxes larger than the sun, explains Pavlidis.

“Chipmakers need new ways to measure temperatures with smaller dimensions,” he says.

Dominic Mailen and Francis Vazquez, doctoral candidates in mechanical, aerospace and manufacturing engineering at Pavlidis, UConn, have worked with colleagues at the U.S. Navy Institute over the past year to tackle the challenge of measuring heat output. Their work brought about a “viewpoint” paper published in Applied Physics Letters.

“The “viewpoint” paper is an upcoming summary, aimed at encouraging other researchers to look into similar topics,” says Myren, a graduate fellow in the Department of Defense Science and Engineering with seven years of R&D experience in engine control related to fuel systems, internal combustion, and engine control.

“The push now is developing a thermal management strategy for broad, ultra-width bandgap semiconductor devices. We have many unresolved questions and we are working hard in Dr. Publidis’s lab, but cross-pollination of ideas is how academic circles thrive.”

In an article entitled “Emerging Thermal Metrology of Ultra Awid Band-Gap Semiconductor Devices,” the co-authors discuss the advantages and disadvantages of using UWBG materials in semiconductors and outline some innovative technologies for measuring temperature at a microscale. These methods help engineers design faster, more powerful electronic devices without the risk of overheating.

After the paper was run online in late May, the co-authors received an unexpected note from the editor of Applied Physics Letters. “[We] Your article felt remarkable and chose to be promoted as an editor’s pick. It will be posted to the journal’s homepage and the badge will appear next to the title. ”

“It’s not a small feat to have a publication chosen as the editor’s pick in the highly acclaimed applied physics writing that publishes over 2,000 articles a year,” says JC Zhao, dean of UConn College of Engineering. “Professor Publidis and his group congratulate us on this recognition and we are extremely proud of their achievements.”

Vazquez’s specific research interests are thermal management for high power and radio frequency (RF) power electronics. In Pavlidis’s lab, he enjoys a combination of research and meaningful applications, solving the real challenges of electronics and photonics that directly affect energy efficiency, reliability and performance.

“What really makes this experience special is the culture of the lab,” says Vazquez. “Professor Pavlidis is incredibly supportive and patient, especially when we run into knowledge that is difficult to explain, and he always encourages us to be curious.

“His approach explores new ideas and rigorously tests them, and thinks about how our work translates into real-world innovation. It’s a combination of intellectual freedom and high standards that will excite me in the lab every day.”

In the paper, researchers explore several options for measuring the temperature of UWBG devices. They propose to use optical methods such as Raman spectroscopy and light to measure temperature-dependent properties. Electrical methods: Use electrical signals to sense temperature and scan probe methods such as thermal microscopes to scan the temperature and feel heat when touching the surface.

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, and measuring how light is absorbed by material defects to calculate the temperature of gallium oxide electronics. They are also working on a new kind of microscope that can use deep UV rays to see very small heat patterns.

“These proposed methods provide solutions for measuring peak temperatures in future electronics. This is a key indicator of when devices will break down. Providing accurate metrology to the industry will lower barriers to commercialization and enable engineers to develop new thermal management strategies,” says Pavlidis.

This group’s research is supported by Microelectronics Commons, a program specifically created to commercialize UWBG devices for electronic devices. The Commons program has established the Northeast Microelectronics Coalition Hub, a network of over 200 organizations, academic institutions, commercial and defense companies, and federally funded centers concentrated in eight Northeastern states. The paper idea came from a project that Publidis worked as an office for a Navy Researcher last summer.

This month, Pavlidis envisions working with semiconductor partners this month to develop an affordable strategy to lower temperatures in electronic devices. By pushing in resolution limits for temperature measurements, the lab plans to extend methods to improve other technologies such as quantum computing and photonic circuits.

They are already working with colleagues at the University of Maryland to design photonic hardware for next-generation data storage. The study is published in Nature Communications.

“We hope that our work has laid the foundation for thermal design for the next generation of UWBG devices,” says Pavlidis.