Thermal Performance Improvement of GaN-on-Diamond High Electron Mobility Transistors

III-Nitride high electron mobility transistors (HEMTs) have been of critical importance for commercial and military applications which require the high frequency, high power density enabled by the favorable properties of Gallium Nitride. However, the long-term reliable operation of GaN at high power has continued to face unique challenges originating from the simultaneously high electric field and high temperature within a small volume of a HEMT [1]. Mitigating self-heating using a CVD diamond cap have resulted in about 20% lower device temperature at the expense of additional process complexity in order to integrate the heat spreading close to the 2DEG channel [2]. Similarly, GaN -on-diamond technology has produced excellent electrothermal performance by integrating GaN -on-Si with CVD diamond growth on the N-polar back side [3]. Such advances in thermal management have demonstrated that GaN HEMTs have the potential to operate reliably at very high power density . In this work, we have quantified the electrothermal performance of state-of-the-art AIGaN/GaN HEMTs on Si and diamond substrates and demonstrate very high DC output power operation at a reliably low temperature.