Auburn, AL - Researchers at Sandia National Laboratories and Auburn University have developed a new method to more accurately detect atomic-scale defects in electronic materials, an advance that could help improve technologies ranging from electric vehicles to high-power electronics. The study, recently accepted for publication in the Journal of Applied Physics, addresses a longstanding challenge in understanding what happens at the critical boundary where a semiconductor meets an insulating layer.
At this interface, microscopic defects can trap electrical charge and quietly reduce device performance, even when the device otherwise appears to function normally. These defects can limit efficiency, increase electrical losses, and reduce the performance of advanced semiconductor devices.
Scientists commonly study these defects by comparing how a device responds to slow and fast electrical signals. However, the technique depends on knowing a key device property, the insulator capacitance, with very high accuracy. Even tiny errors can produce misleading results, sometimes making it appear that far more defects exist than are actually present.
The problem is like tuning a radio. If the frequency is slightly off, the sound becomes distorted. If it is far off, only noise is heard. Only at the correct setting does the signal come through clearly. In these measurements, researchers are effectively trying to "listen" to the defects, with the assumed capacitance acting as the tuning dial. However, unlike a radio listener who easily recognizes a clear broadcast, researchers do not inherently know what the true defect signal should look like. If this tuning parameter is not set exactly, the resulting data cannot be trusted.
Instead of relying on estimates, the researchers developed a physics-based framework that identifies the correct device conditions automatically by enforcing a fundamental electrostatic constraint. In simple terms, all the voltages inside the device must add up consistently according to the laws of physics. By enforcing this condition, the method removes guesswork and allows researchers to accurately measure defects in regions where the technique previously failed, particularly near the semiconductor band edge, where defects can have the strongest impact on device behavior.
"This work resolves an otherwise fundamental limitation in one of the most widely used techniques for studying semiconductor interfaces," said Brian D. Rummel, senior member of technical staff at Sandia National Laboratories and lead author of the study. "By introducing a physically consistent framework, we can now extract information that was previously obscured by measurement uncertainty."
The advance is particularly important for semiconductor materials such as silicon carbide and gallium nitride, which are widely used in high-efficiency and high-power electronics. These materials are central to technologies including electric vehicles, renewable energy systems, and advanced power conversion devices, but their performance is often limited by defects at material interfaces. By providing a more accurate way to measure these defects, the new method gives researchers a clearer understanding of what is happening inside the device and how to improve it.
"The new analytical framework will help researchers more accurately measure defects in transistor materials," said Sarit Dhar, professor of physics at Auburn University and co-author of the study. "We are excited to apply this method to measure a variety of technologically relevant and exploratory interfaces in our future work."
"Defects at semiconductor interfaces play a major role in determining the performance and reliability of power electronic devices," said Robert J. Kaplar, senior scientist and manager of the semiconductor materials and device physics group at Sandia National Laboratories. "More accurate characterization tools help us better understand these materials and ultimately improve next-generation electronic technologies."
At its core, the work improves a widely used semiconductor measurement technique by ensuring that it remains fully consistent with fundamental physical principles. Like tuning a radio to the correct frequency, the framework helps researchers separate meaningful signals from noise and obtain a clearer picture of the microscopic defects that influence device performance. As demand grows for faster, more efficient, and more reliable electronics, advances such as this one could help guide the development of next-generation semiconductor technologies.
