Thermophysical Property Measurement of GaN-on-AlN Wafers for Next-Generation RF Device Technologies Available to Purchase

Gallium nitride (GaN) high electron mobility transistors (HEMTs) play a crucial role in modern radio frequency (RF) power amplifiers. However, the performance and reliability of GaN HEMTs are negatively impacted by device self-heating. Hence, it’s imperative to thoroughly characterize the entire thermal resistance network within the material stack to pinpoint any bottleneck resistance components. In this study, a multi-frequency, multi-spot time-domain thermoreflectance measurement approach was used to measure the thermal resistance associated with the constituent layers and interfaces within a GaN-on-AlN wafer stack. The thermal conductivity of the GaN layer and the AlN substrate in both through-plane and in-plane directions were determined. The GaN/AlN interface exhibits a high thermal boundary conductance (TBC) of 500 MW/m²·K. This surpasses previously reported TBC values across GaN/SiC and GaN/diamond interfaces, highlighting the potential for improved thermal management of GaN HEMTs.