Anomalous Thermal Transport Driven by Electron–Phonon Coupling in 2D Semiconductor h‐BP

• Published in: Advanced functional materials 2022-11, Vol.32 (45), p.n/a
• Main Authors: Zhou, Zizhen, Yang, Xiaolong, Fu, Huixia, Wang, Rui, Lu, Xu, Wang, Guoyu, Zhou, Xiaoyuan
• Format: Article
• Language: English
• Subjects: Bilayers; Broken symmetry; Coupling; Doping; electron–phonon coupling; first‐principles calculations; Heat conductivity; Heat transfer; Heat transmission; Materials science; one‐atom‐thick 2D materials; Phonons; Scattering; Semiconductors; Thermal conductivity; Transport phenomena
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202206974

The electron–phonon coupling (EPC) in semiconductors is typically much weaker than phonon–phonon scattering and its effect on lattice thermal conductivity κl has long been considered negligible. Herein, using first‐principle calculations, it is discovered that the EPC can be significant or even dominant over the intrinsic phonon–phonon scattering via doping in 2D semiconductor hexagonal boron phosphorus (h‐BP). Filling electron pocket till van Hove singularity gradually strengthens the EPC and consequently diminishes the room‐temperature κl by 25% and 80% for monolayer and bilayer h‐BP, respectively. Strikingly, at high doping levels, the EPC drives phonon transport in bilayer h‐BP to an anomalous regime where κl becomes nearly temperature (T) independent deviated from the intrinsic 1/T trend. This distinctive behavior is governed by the joint effects of horizontal mirror symmetry breaking, and weak phonon–phonon scattering stemming from the predominance of normal processes. Further considering electronic contributions, the abnormal T‐independent thermal conductivity is still reserved, thereby facilitating the experimental exploration of EPC effect on κl. This study unveils the exotic thermal transport phenomenon in one‐atom‐thick 2D semiconductors and offers a unique avenue to manipulate heat flow by externally controlling the EPC, which calls for future experimental verification. Significant electron‐phonon coupling is discovered in a 2D semiconductor bilayer h‐BP that even dominates over the intrinsic phonon‐phonon scattering well above room‐temperature, which drives phonon transport to an anomalous regime with temperature independent κl. This abnormal behavior is first observed in a semiconductor with minor electronic thermal conductivity, facilitating the experimental exploration of electron–phonon coupling impact on heat transport.