GaN (Gallium Nitride) High Electron Mobility Transistor (HFET) devices face severe thermal control problems as a result of high power densities which result from the need for more power and the ongoing reduction in geometries of individual devices. The device lattice temperature increases under high power causing several detriment effects: a) The carrier phonon scattering rate increases causing a reduction of the carrier mobility and an increase of the device resistance. Under certain bias conditions, the increase of device on-resistance could lead to an increase of the dissipated power and therefore a destructive thermal run-away. b) High lattice temperature increases the reliability risk and decreases the device lifetime. The Velox team proposes transferring and optimizing the existing AlGaN/GaN HFET MOCVD epitaxial deposition and device fabrication process developed by Velox Semiconductor Corp. on Si to a high thermally conductive silicon-on-diamond substrate developed by sp3 Inc. The team also intends to demonstrate initial devices for power inverters and converters in power supplies supporting X-band radar utilizing these substrates. This solution can provide a significant device performance and reliability improvement due to better device thermal management. The complete achievement of the Phase I goals will set the baseline process flow for device fabrication.
Keywords: High Electron Mobility Transistor Hfet Silicon-On-Diamond Thermal Management
