Prediction and measurement of thermal transport across interfaces between semiconductor and adjacent layers

• TBC of multilayer structures is reconstructed by modified two color TDTR.
• Al-semiconductor TBC decreases with increasing average phonon velocity.
• Prediction of TBC is improved by DMM with phonon attenuation constant.

The thermal boundary conductance between multilayer structures including Al film, semiconductors with high Debye temperatures (GaN, AlN, Si, diamond) and dielectric substrates (sapphire) has been measured using a two-color femtosecond laser pump-probe system (a variation of transient time-domain thermoreflectance, TDTR). The thermal boundary conductance for the combinations of semiconductors and dielectrics falls within a relatively narrow range, 10–20 MW m−2 K−1, at room temperature. The measured thermal boundary conductance between Al film and semiconductor or dielectric substrates is one order of magnitude larger than that between semiconductor and dielectric substrates. A modified diffuse mismatch model (DMM) is used to interpret the data and extract the phonon transmissivity at the interface. The predicted results of the DMM corrected by attenuation constant agree well with the experimental values. Over a wide phonon velocity, both the measured and predicted results decrease with the increasing average phonon velocity. Both the vibration mismatch and changes in the localized phonon transport near the interface contribute to the reduction in thermal boundary conductance. Other scattering mechanisms are discussed which may explain the failure of the DMM at room temperature.