Cornell University researchers have created a new type of transistor that could transform high-power wireless electronics, making future communication systems faster, more reliable, and easier to build within the United States.
The innovation also helps reduce dependence on gallium, a semiconductor material facing global supply challenges.
The new device is called an XHEMT, a specialized transistor built by placing an ultra-thin layer of gallium nitride on top of a thick, high-quality aluminum nitride crystal.
Aluminum nitride is an extremely tough semiconductor with a very wide bandgap, meaning it can handle high voltages and temperatures while losing much less energy.
These qualities make it ideal for electronics that must deliver high performance under intense conditions.
The research team was co-led by professors Huili Grace Xing and Debdeep Jena, along with doctoral student Eungkyun Kim. Their study was published in Advanced Electronic Materials.
The XHEMT is designed for devices such as radio-frequency power amplifiers, which are essential for 5G and future 6G wireless networks, as well as radar systems used in national defense.
These systems must push large amounts of power at very high frequencies, which generates heat and can limit performance.
Kim explained that aluminum nitride’s excellent thermal conductivity helps solve this problem.
Because it removes heat more effectively, the transistor’s channel stays cooler than in current technologies.
Cooler operation means the device can handle even more power, potentially increasing the range of wireless communication or improving radar strength.
A major advantage of the XHEMT comes from how perfectly the material layers line up, or “lattice-match.”
Traditional gallium nitride devices grown on silicon, sapphire, or silicon carbide often contain many crystalline defects—tiny imperfections that can weaken performance and shorten device life.
The new aluminum nitride structure reduces these defects by about a million times. Xing said that this dramatic improvement could lead to major performance and reliability gains as the technology advances.
The project also addresses a growing concern: the global supply of gallium. Gallium nitride is widely used in electronics, and more than 90 percent of the world’s gallium supply comes from outside the United States.
Export restrictions and supply disruptions have raised concerns for U.S. manufacturing.
According to Jena, the new transistor design uses only a very small amount of gallium, reducing reliance on the material by several orders of magnitude while still achieving high performance.
The aluminum nitride crystals used in the research were grown by Crystal IS, a company in Albany, New York, and one of the few manufacturers capable of producing crystals of this quality. While aluminum nitride has mainly been used in photonics, the Cornell team’s work opens the door for its use in high-power electronics as well.
Recent progress, reported in APL Materials, shows that the XHEMT structure can now be grown on 3-inch wafers, bringing it closer to commercial production.
The Cornell team—including doctoral student Yu-Hsin Chen, research associate Jimy Encomendero, and doctoral student Naomi Pieczulewski working with professor David Muller—developed and studied the material layers in detail to understand their atomic structure.
This breakthrough could help launch a new generation of faster, stronger, and more resilient wireless technologies built with U.S.-grown materials.
Source: Cornell University.
