Thermal Modeling of High Power GaN-on-Diamond HEMTs Fabricated by Low-Temperature Device Transfer Process

We report on a novel fabrication process of GaN-on-Diamond high electron mobility transistors (HEMTs) and its resulting thermal performance enhancement over conventional GaN-on-SiC technology. In this process, GaN devices are first fabricated on their epitaxial substrate (e.g. sapphire or SiC) before being removed from the original substrate and bonded onto a high-thermal-conductivity diamond substrate at low temperature. Process flow and technology progress is described. Finite-element thermal analysis is performed to quantify the thermal performance improvement of our GaN-on-Diamond design over conventional GaN-on-SiC technology together with the impact of thermal boundary resistance at the GaN/diamond bonding interface.