Samsung Electronics' gallium nitride (GaN) power semiconductor foundry project has hit a setback during trial production, and commercial output may now slip beyond the current target date.

Multiple industry sources reported on July 31 that some test chips stopped functioning after exposure to temperatures of 100 to 200 degrees Celsius for roughly 1,000 hours. Samsung had run the trial with chips designed by fabless semiconductor customers.

The company built a dedicated 8-inch GaN foundry line at its Giheung campus in Yongin with monthly capacity of approximately 1,300 to 1,500 wafers. That line now sits at the center of an investigation into why devices failed extended high-temperature testing.

GaN semiconductors routinely serve high-voltage applications up to 1,200 volts and environments exceeding 200 degrees Celsius. Their reliability under such conditions drives demand from electric vehicle, robotics and data center customers. Industry sources said the reported failures could limit the usability of chips built on the current process.

Samsung is investigating the root cause. The wafer manufacturing process is the leading area of focus, according to those sources. Process modifications introduced to hit targeted device performance may have contributed to the problem.

GaN devices are typically fabricated on epitaxial wafers, where a GaN layer grows on a silicon wafer through an epitaxy process. If the quality or structure of that GaN layer is not fully optimized, defects become more pronounced under high-temperature, high-voltage operation. Samsung produces its own epitaxial wafers using metal-organic chemical vapor deposition (MOCVD) equipment.

One person familiar with the matter said Samsung may have prioritized hitting the target threshold voltage of 2 to 3 volts for power semiconductors while overlooking effects on device longevity. GaN semiconductors generally require a threshold voltage of around 2 volts. Set the threshold too low, and the device responds to very small currents and becomes more susceptible to operational errors.

Schedule already slipped once

Samsung reorganized its LED business in 2023 and established the Compound Semiconductor Solutions (CSS) division to focus on GaN. The division originally planned to launch the dedicated foundry line in 2025. Weak power semiconductor market conditions pushed that schedule to the end of 2026.

Industry sources now expect the reliability issue to delay the timeline by several additional months.

One Samsung GaN foundry customer, speaking on condition of anonymity, said Samsung entered the market later than competitors because it prioritized major businesses such as memory semiconductors. Infineon Technologies, STMicroelectronics, Texas Instruments and Innoscience have been shipping GaN semiconductors commercially for one to two years.

Some fabless companies are evaluating alternative foundry partners until Samsung resolves the issue. Candidates include GlobalFoundries, Powerchip Semiconductor Manufacturing Corporation and X-FAB. Unlike silicon semiconductors, where high mask costs typically push production toward a single foundry, compound semiconductor mask costs run lower. Working with multiple manufacturing partners is therefore less burdensome.

A Samsung Electronics representative said the company remains in the pre-production stage and is working through normal development challenges.

"It is part of the process of addressing trial-and-error issues before mass production," the representative said. "It is too early to determine whether these findings constitute a defect."