New epitaxial buffer layer schemes for avalanche-capable GaN power switching devices – AVALGaN

In AVALGAN project, a new kind of GaN-on-Silicon structures will be developed for demonstrating a power switching high electron mobility transistor capable of withstanding voltages higher than 1200 V. Beyond the challenges associated with the lack of GaN substrate and the need to resort to hetero-epitaxy of these materials on large, inexpensive Silicon substrates, the industrial development of power components faces limitations related to the phenomenon of breakdown in Silicon, which necessitates the use of very thick GaN films. Thanks to an avalanche phenomenon occurring in GaN, the new structures proposed by the project will, with thinner films, avoid the destruction of devices as is usually the case due to destructive breakdown in Silicon. Additionally, this should allow for the design of structures capable of withstanding high voltages with GaN films containing less carbon, which is advantageous for reducing losses during switching (dynamic resistance degradation phenomenon). These ideas have been the subject of a first proof of concept at lower voltage with thin films, and a patent application is pending. However, technical difficulties remain in achieving optimal epitaxial layers, consistent with our new approach and capable of withstanding a voltage of 1400V. The objective of the project is to overcome these barriers, which will enable the fabrication of original and more efficient electronic devices. The project gathers 3 laboratories and a company. CRHEA coordinates the project, explores various epitaxial strategies by MBE, MOVPE or their combination, and conducts material characterizations. The startup EasyGaN develops the MBE process on a production tool with 200 mm diameter capacity. LN2 designs the structures, manufactures the components, and performs low-voltage electrical characterizations. Electrical characterizations in continuous and pulsed modes are conducted under high voltage at LAAS to demonstrate the advantages of these new devices.