Suppressing frequency dispersion in GaN FETs
As part of a project commissioned by Japan’s Ministry of the Environment, Mitsubishi Electric has explained the frequency dispersion caused by crystal defects in a high-frequency GaN transistor made by depositing a GaN epitaxial layer on a GaN substrate.
As part of the project, the company showed that dispersion can be significantly suppressed to obtain flat frequency characteristics.
Details will be presented at the International Workshop on Nitride Semiconductors 2026 (IWN2026), to be held from November 8 to 13 at Kumamoto Castle Hall in Kumamoto City, Japan.
According to Mitsubishi this is a world first that makes it possible to boost performance, shrink device size, and cut power consumption of high-frequency equipment, including industrial microwave heating systems that use GaN transistors.
Conventional GaN transistors have mainly been fabricated by forming a GaN epitaxial layer on a SiC substrate because SiC has high thermal conductivity and provides effective heat dissipation. However, crystal defects have been unavoidable during the film formation process due to the difference in materials between the substrate and the epitaxial layer.
These crystal defects impede the movement of electrons during high-frequency operation, causing frequency dispersion, in which current values vary depending on the frequency, and resulting in unstable device operation.
Consequently, complex correction using digital circuits had previously been required, making increased overall system size and greater power losses significant challenges. Mitsubishi Electric says its breaktrough makes it possible to simplify these digital correction circuits.
