Importance of electron-phonon coupling in thermal transport in metal/semiconductor multilayer films

Thermal transport across the interface between metals and semiconductors is ubiquitous in micro-and nano-manufacturing devices. The direct simulation of thermal transport in such multilayers is rarely stud-ied due to different main carriers involved, such as electrons in metals and phonons in semiconduc-tors. This study investigates thermal transport in metal/semiconductor multilayer films using the cou-pled electron and phonon Boltzmann transport equations combined with the phonon diffuse mismatch model. The calculated overall thermal conductivity demonstrates the importance of electron-phonon cou-pling transport and then the present work gives a critical thickness of the metal layer for considering electron-phonon coupling transport. If only one side of the metal layer is in contact with the semicon-ductor, the electron-phonon coupling transport in metal layer should be considered when the metal layer thickness is larger than 12.5 nm, 7.5 nm and 2 nm for Au/Si, Cu/Si and Al/Si bilayer films, respectively. This critical thickness will be approximately double if two sides of the metal layer are both in contact with the semiconductor due to the non-equilibrium between electrons and phonons at both sides, such as the super-lattice with infinity periods. Additionally, there exist a minimum thermal conductivity in metal/semiconductor multilayers when changing the thickness of the metal layer. This work will promote a deeper understanding of the thermal transport in metal/semiconductor multilayers at the micro and nanoscale and provide the insightful indication for the manipulation of thermal conductivity in multilay-ers.(c) 2022 Elsevier Ltd. All rights reserved.