Chinese researchers have discovered the leading cause of defects in the promising semiconductor material gallium nitride (GaN). This material is critical for developing advanced electronics, specifically those used for military applications.
The team, led by Professor Huang Bing and his team at Peking University, identifies the leading cause of defects in GaN crystal growth. GaN fabrication typically uses substrates like silicon and sapphire to support growth.
They found that the issue stems from dislocation defects, which disrupt the crystal structure, leading to leakage and reduced performance. The team found these defects because GaN has a hexagonal atomic structure, which makes it different from silicon’s cubic structure.
This differs from silicon defects, which are typically caused by gliding (a movement along a plane), which the industry has learned to control. GaN defects, on the other hand, are primarily due to climbing (changes in the number of local atoms), a process that has been poorly understood until now.
Why is GaN important?
GaN is a third-generation semiconductor material commonly used in 5G base stations, radar, military communications, aerospace, and electronic warfare. It is better than silicon in specific applications due to its ability to operate at higher voltages, frequencies, and temperatures.
At present, major world powers, like the United States, rely heavily on GaN for advanced chips. This makes it strategically important in the ongoing U.S.-China tech rivalry.
China controls around 98% of global gallium production and has recently banned exports to the U.S. This has driven up the cost of GaN-based semiconductors, making it harder for the U.S. (especially the Pentagon) to source affordable chips.
The U.S. Geological Survey (USGS) warns that the economic impact will be significant, affecting industries that rely on GaN-based chips.
The team made their discovery thanks to a clever use of scanning transmission electron microscopy (STEM). Using this technology, they observed atomic-scale dislocations for the first time.
They discovered that “tuning the Fermi level” (adjusting the energy levels of electrons) can control the climbing process and reduce defects. This “Fermi energy level” can be likened to the “water level” of the electronic world.
A big deal for China
It marks the highest stable energy electrons can have. It determines whether and how easily a semiconductor conducts electricity. By introducing specific impurities and increasing gate voltage, they minimized dislocations in GaN fabrication.
“Traditional strategies to avoid defects include using different substrates and adjusting crystallization temperatures, but these approaches only address the symptoms, not the cause,” said Professor Huang Bing with the Beijing Computational Science Research Centre on Tuesday.
If China can perfect low-cost, high-quality GaN manufacturing, it could widen the semiconductor price gap, making Chinese chips more competitive. Since the U.S. depends on GaN for military applications, these developments could increase China’s strategic advantage in electronics and defense.
If reports on the findings are accurate, it marks a significant step toward improving the efficiency and reducing the cost of GaN-based semiconductors. If China can mass-produce high-quality GaN chips, it could increase its lead in semiconductor technology, especially in military and 5G applications.
