Nanocrystalline Diamond Integration with III-Nitride HEMTs

Reduced performance in Gallium Nitride (GaN)-based high electron mobility transistors (HEMTs) as a result of self-heating has been well-documented. To mitigate this effect, the incorporation of high thermal conductivity diamond heat spreading films or substrates has been proposed. A mid-process integration scheme, termed "gate-after-diamond," is shown to improve the thermal budget for NCD deposition and enables scalable, large-area diamond coating without degrading the Schottky gate metal. The optimization of this process step is presented in this work. Nanocrystalline (NCD)-capped devices had a 20% lower channel temperature at equivalent power dissipation. Improved electrical characteristics were also observed, notably improved on-resistance and breakdown voltage, and reduced gate leakage.