Intrinsically large effective mass and multi-valley band characteristics of n-type Bi_(2)eBi_(2)Te_(3)superlattice-like films  

作　　者：Yujie Ouyang Min Zhang Fangyang Zhan Chunxia Li Xianda Li Fan Yan Sen Xie Qiwei Tong Haoran Ge Yong Liu Rui Wang Wei Liu Xinfeng Tang 

机构地区：[1]State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan,430070,China [2]International School of Materials Science and Engineering,Wuhan University of Technology,Wuhan,430070,China [3]Institute for Structure and Function&Department of Physics,Chongqing University,Chongqing,400044,China [4]School of Physics and Technology and the Key Laboratory of Artificial Micro/Nano Structures of Ministry of Education,Wuhan University,Wuhan,430072,China

出　　处：《Journal of Materiomics》2024年第3期716-724,共9页无机材料学学报（英文）

基　　金：Y.J.Ouyang and M.Zhang contributed equally to this work.The work was supported by National Key Research and Development Program of China(Grant No.2021YFA0718700,2019YFA0704900);the National Natural Science Foundation of China(Grant No.92163211);State Key Laboratory of Advanced Technology for Materials Synthesis and Processing of Wsluhan University of Technology(2023-KF-1).

摘　　要：Thermoelectric superlattices are expected to decouple the strong correlation between various thermo-electric parameters,and are an important strategy for excellent thermoelectric performances.The superlattices of(Bi_(2))m(Bi_(2)Te_(3))n homologous series are well-known for low lattice thermal conductivity and intriguing topological surface states.However,the impacts of electronic structure on the thermo-electric performance were still not well-understood in(Bi_(2))m(Bi_(2)Te_(3))n.To cope with this issue,Bi_(2)eBi_(2)Te_(3)superlattice-like films with adjustable Bi_(2)/(Bi_(2)+Bi_(2)Te_(3))molar ratio(R)were successfully fabricated by the molecular beam epitaxy technique.Angle-resolved photoemission spectroscopy measurements com-bined with theoretical calculations revealed the conduction band evolution from single-valley to multi-valley as R≥0.30,leading to intrinsically high carrier effective mass and improved thermoelectric power factor.Also,the superlattice film(R=0.46)with the structure close to Bi_(4)Te_(3)possesses the topological surface state feature around the high symmetry point.As a result of the high effective mass of 3.9 m0 and very high electron density of_(2).31×10^(21)cm^(-3),the film with R=0.46 acquired the highest power factor of 1.49 mW·m^(-1)·K^(-2)at 420 K,outperforming that of other(Bi_(2))m(Bi_(2)Te_(3))n superlattices.This work lays an essential foundation on understanding the electronic structure and further improving thermoelectric performances of(Bi_(2))m(Bi_(2)Te_(3))n homologous series.

关 键 词：Bi_(2)eBi_(2)Te_(3)superlattice Molecular beam epitaxy Band structure Thermoelectric performance 

分 类 号：TQ17[化学工程—硅酸盐工业]