We show that the use of sub-nm adhesion layers significantly enhances the thermal interface conductance at metal-dielectric interfaces. A metal-dielectric interface between Au and sapphire (Al 2 O 3 ) was considered using Cu (low optical loss) and Cr (high optical loss) as adhesion layers. To enable high throughput measurements each adhesion layer was deposited as a wedge such that a continuous range of thickness could be sampled. Our measurements of thermal interface conductance at the metal-Al 2 O 3 interface made using frequency domain thermoreflectance show that a 1 nm thick adhesion layer of Cu or Cr is sufficient to enhance the thermal interface conductance by more than a factor of 2 or 4, respectively, relative to the pure Au-Al 2 O 3 interface. The enhancement agrees with the Diffuse Mismatch Model-based predictions of accumulated thermal conductance versus adhesion layer thickness assuming that it contributes phonons with wavelengths less than its adhesion layer thickness, while those with longer wavelengths transmit directly from the Au.

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