On the importance of using exact full phonon dispersions for predicting interfacial thermal conductance of layered materials using diffuse mismatch model

Abstract

Several models have been employed in the past to estimate interfacial thermal conductance (ITC) for different material interfaces, of which the diffuse mismatch model (DMM) has been generally accepted as reliable for rough material interfaces at high temperature. Even though the DMM has been shown to predict the correct order of magnitude in isotropic material interfaces, it is unable to reproduce the same accuracy for low-dimensional anisotropic layered materials, which have many potential applications. Furthermore, the use of approximated dispersion curves tends to overestimate the ITC. In this work, we propose a new method that utilizes a mode-to-mode comparison within the DMM framework to predict ITC. We employed this model to calculate ITC between layered materials such as MoS2 and graphite and metals such as Al, Au, and Cr. We then compared our values with previous literature data that employ linear dispersion relations and experimental data from time-domain thermoreflectance measurements. This new framework was then used to visualize the phonon focusing effect in anisotropic materials. Further analysis revealed that counting only the three acoustic modes and neglecting the low-frequency optical modes lead to significant underestimation of the ITC using DMM. Our findings indicate that it is imperative to use the exact full phonon dispersion relations in evaluating the ITC for low-dimensional layered materials.

In-Plane Thermoelectric Properties of Flexible and Room-Temperature-Doped Carbon Nanotube Films

“…The temporal decay of the measured signals is used to deduce κ with a heat diffusion model. , In principle, the thermal model used for analyzing the TDTR experiment consists of seven parameters: thickness, volumetric heat capacity and κ of the transducer [in this case aluminum (Al)] film, diameter of the laser spot, thermal conductance of the Al/MWCNT interface, and κ and volumetric heat capacity of the MWCNT sample. Of these, κ of the MWCNT film and interfacial thermal conductance are varied to fit the data. , Other experimental and modeling details are similar to the one described in previous works. , This method has been used to measure various porous thin films and network structures. − …”

“…53,54 Other experimental and modeling details are similar to the one described in previous works. 52,55 This method has been used to measure various porous thin films and network structures. 56−61 In-plane thermal conductivity measurement of MWCNT films using TDTR requires additional sample preparation steps.…”

Anisotropic Thermal Conductivity of Crystalline Layered SnSe2

“…Then, we fix k z and fit the experimental data in a high frequency range (1–40 MHz) to estimate simultaneously R 1 and R 2 . For the first estimate to determine the value of the free parameters ( k z , R 1 , and R 2 ), we used previous reported values of similar materials. − A typical example of the recorded phase signal and corresponding best model fit for a 130 nm thick SnSe 2 film is shown in Figure d. The inset to Figure d shows the fitting of our experimental data in the high frequency range.…”

Bonding‐Enhanced Interfacial Thermal Transport: Mechanisms, Materials, and Applications

“…[ 32 ] The DMM model is based on two main assumptions: first, the phonon transmittance is isotropic, that is, the transmittance is independent of the phonon incident angle; Second, phonons will lose all memory after diffuse scattering at the interface, that is, photons will be emitted from the interface to both sides according to probability according to VDOS of materials on both sides at the interface. [ 35 ] Although the prediction of DMM model is better than that of AMM model near room temperature, the research of Stevens et al. [ 36 ] shows that the prediction results of DMM model are still at least one order of magnitude different from the experimental values.…”