Thermal resistance at a twist boundary and a semicoherent heterointerface

Abstract

Traditional models of interfacial phonon scattering, including the acoustic mismatch model (AMM) and diffuse mismatch model (DMM), take into account the bulk properties of the material surrounding the interface, but not the atomic structure and properties of the interface itself. Here, we derive a theoretical formalism for the phonon scattering at a dislocation grid, or two interpenetrating orthogonal arrays of dislocations, as this is the most stable structure of both the symmetric twist boundary and semicoherent heterointerface. With this approach, we are able to separately examine the contribution to thermal resistance due to the step function change in acoustic properties and due to interfacial dislocation strain fields, which induces diffractive scattering. Both low-angle Si-Si twist boundaries and the Si-Ge heterointerfaces are considered here and compared to previous experimental and simulation results. This work indicates that scattering from misfit dislocation strain fields doubles the thermal boundary resistance of Si-Ge heterointerfaces compared to scattering due to acoustic mismatch alone. Scattering from grain boundary dislocation strain fields is predicted to dominate the thermal boundary resistance of Si-Si twist boundaries. This physical treatment can guide the thermal design of devices by quantifying the relative importance of interfacial strain fields, which can be engineered via fabrication and processing methods, versus acoustic mismatch, which is fixed for a given interface. Additionally, this approach captures experimental and simulation trends such as the dependence of thermal boundary resistance on the grain boundary angle and interfacial strain energy.

Microscale Imaging of Thermal Conductivity Suppression at Grain Boundaries

“…The trend is in agreement with literature predictions suggesting a misorientation dependence of the thermal resistance. [ 19,20,48 ] The average R B for the GBs in our measurement is 75 ± 22 m 2 K GW −1 . These values are roughly five times larger than the TBR reported for silicon, [ 19 ] and around one order of magnitude larger than that reported for diamond.…”

“…It has been proposed that the GB energy increases with the misorientation angle, [ 47 ] in turn leading to higher thermal resistance. [ 48 ] In the model proposed by Read and Shockley, [ 47 ] low‐angle GBs are described as an array of dislocations. The spacing between the dislocations, and thus the phonon scattering strength of their strain fields, are related to the GB angle.…”

“…This accounts for the angle‐dependent thermal resistance. [ 48 ] This model applies to phonons. However, GBs and dislocation strain are known to affect charge carrier propagation as well.…”

Synergetic Enhancement of Strength–Ductility and Thermoelectric Properties of Ag2Te by Domain Boundaries

“…[48][49][50] Thus, the nanodomain boundaries and surrounding strain fields (Figure 5b) can strongly scatter the phonons of both low-and high-frequency. [51,52] The inhomogeneous internal strain fields can not only introduce phonon scattering centers, but also induce lattice softening, which leads to reduced speed of sound (Table S2, Supporting Information). [53] The 𝜅 L decreases from 0.22 W m −1 K −1 for Ag 2 Te-0% to 0.18 W m −1 K −1 for Ag 2 Te-10% at 400 K, which is close to the theoretical minimum 𝜅 min (Figure S18, Supporting Information).…”

A Review on Phonon Transport within Polycrystalline Materials

“…[58] Some calculations also revealed the importance of the interfacial strain field. [20,[57][58][59] As more advanced techniques, MD simulations [35][36][37]60] and AGF analysis [38][39][40][41][42][43] can provide more insights into the interfacial phonon transport. The disordered interface layer can be incorporated into such simulations though an oversimplified interfacial atomic structure is still used in most studies.…”