Suppression of intervalley scattering and enhanced phonon anharmonic interactions in 2D Bi_(2)TeSe_(2):Crystal-field symmetry and band convergence  

作　　者：Lei Peng Ao Wu Yujie Xia Haotian Zhang Yuting Yang Hezhu Shao Ying Chen Juan Zhang Le Shu Heyuan Zhu Yuxiang Zheng Hao Zhang 

机构地区：[1]School of Information Science and Technology,Department of Optical Science and Engineering,Fudan University,Shanghai 200433,China [2]College of Electrical and Electronic Engineering,Wenzhou University,Wenzhou 325035,China [3]Department of Light Sources and Illuminating Engineering,Fudan University,Shanghai 200433,China [4]Yiwu Research Institute of Fudan University,Yiwu 322000,China

出　　处：《Journal of Materiomics》2024年第2期386-395,共10页无机材料学学报（英文）

基　　金：supported by the National Natural Science Foundation of China(62275053,61775042,11674062,11374063);Shanghai Municipal Natural Science Foundation under Grant Nos.19ZR1402900 and the Fudan University-CIOMP Joint Fund(FC2017-003).

摘　　要：The electron-phonon(el-ph)and phonon-phonon interactions play a key role in determining electronic and thermal transport properties,respectively,in promising two-dimensional(2D)semiconductor de-vices.In this study,we investigated el-ph interactions using Wannier-Fourier interpolation method and renormalized phonon scattering considering finite-temperature effects in Bi_(2)TeSe_(2)monolayer.The re-sults show that the optical phonon modes dominate the carrier scattering,where level repulsion induced by crystal field splitting and spin-orbit coupling(SOC)effect effectively suppresses intervalley scattering,leading to high hole mobility.Moreover,the strong anharmonicity in Bi_(2)TeSe_(2)monolayer results in the temperature-dependent softening of its optical phonons,along with a corresponding variation in interatomic force constants(IFCs).As a result,the lattice thermal conductivity is remarkably low and exhibits weak temperature dependence.Finally,the predicted dimensionless thermoelectric figure of merit exceeds unity in the range of 200-800 K,indicating the potential of Bi_(2)TeSe_(2)monolayer for thermoelectric applications.This work provides new insights into the elimination of intervalley scat-tering by crystal field splitting and SOC effects,and paves the way for the evaluation of thermoelectric properties of materials with complex scattering mechanisms and strong anharmonicity.

关 键 词：El-ph interactions Crystal field splitting Spin-orbit coupling Intervalley scattering Renormalized phonon scattering 

分 类 号：O57[理学—粒子物理与原子核物理]