Thermal Performance of GaN Power Transistors on Sapphire Substrate

Gallium nitride high electron mobility transistors (GaN HEMTs) are widely used in the field of power electronics technology due to its advantages of low on-resistance, high blocking voltage and high switching frequency. Sapphire and Si materials are both commonly used as substrate materials in the epitaxial growth of GaN power HEMTs due to their lower price, GaN power HEMTs on sapphire substrate and Si substrate have been realized in the commercial field. However, sapphire is insulated and p-type Si substrate is conductive, on the other hand, sapphire's thermal conductivity is much smaller than that of Si, which may affect the thermal performance of transistors. In this work, we compared the thermal performance of Si-based and sapphire-based commercial GaN power HEMTs, and the thermal performance of sapphire-based GaN HEMT are analyzed, which provides a reference for the application of GaN power HEMT on sapphire in the industry. As the results show, GaN power devices on sapphire substrate has respectable potential.