AlN as interlayer for effective thermal dissipation from gallium nitride to CVD diamond using nanocrystalline diamond seeding

Abstract With the increasing power density achieved in gallium nitride (GaN) electronic devices, the thermal dissipation becomes a key issue that restricts their ultimate performances. However, the effective thermal boundary resistance (TBR eff ) between GaN and their heat spreader usually dominates the heat concentration. Here we introduce a super‐thin AlN interlayer with nanocrystalline diamond (NCD) seeding as the nucleation for the polycrystalline diamond (PCD) film growth on the GaN films. A thermal conductivity approaching 250 W/mK for the 1.2 μm‐thick PCD film is obtained. The TBR eff between GaN and PCD films is estimated to be 5 m 2 K/GW, which is much smaller than that of the typical SiN x interlayer. Since AlN can be deposited simultaneously with the device structure, this work is promising to achieve the full potential of using diamond as the heat spreader for GaN‐based transistors.