Reconstruction of thermal boundary resistance and intrinsic thermal conductivity of SiO2-GaN-sapphire structure and temperature dependence

• TBR is isolated by 3ω method on different thickness film samples.
• Temperature dependence of TBR is dominated by near-interface effect.
• Temperature dependence of TBC is stronger for GaN-sapphire than SiO2-GaN.

The thermal boundary resistance (TBR) between SiO2-GaN film-sapphire is reconstructed by 3ω method in the temperature range of 260–480 K. The TBR at SiO2/GaN film interface is obtained on different samples with different thickness SiO2 films at high frequency of 1 KHz–20 KHz and the TBR at GaN film/sapphire interface is isolated by extending the frequency to a wide range. The measured TBR with strong temperature dependence at GaN film/sapphire interface increases with increasing temperature, and is found to be 1.02 × 10−7 m2 K W−1 at room temperature. The measured TBR with weak temperature dependence at SiO2/GaN film interface decreases with increasing temperature. The temperature dependence of the TBR differs appreciably from the predicted trend by phonon inelastic scattering model and may be affected partially by the lack of some sources of inelastic boundary scattering and the increased diffusive boundary scattering. The predicted results corrected by phonon attenuation process agree well with the experimental values especially at high temperature. The temperature dependence and the larger value of the TBR contain contributions from the near-interface effect including the real boundary between the GaN film and its adjacent layers and the phonon inelastic scattering near the interface region.