Electronic structure of exfoliated millimeter-sized monolayer WSe2 on silicon wafer  

作　　者：Wenjuan Zhao Yuan Huang Cheng Shen Cong Li Yongqing Cai Yu Xu Hongtao Rong Qiang Gao Yang Wang Lin Zhao Lihong Bao Qingyan Wang Guangyu Zhang Hongjun Gao Zuyan Xu Xingjiang Zhou Guodong Liu 

机构地区：[1]Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China [4]Songshan Lake Materials Laboratory,Dongguan 523808,China [5]Beijing Academy of Quantum Information Sciences,Beijing 100193,China

出　　处：《Nano Research》2019年第12期3095-3100,共6页纳米研究（英文版）

基　　金：This work is supported by the National Science Foundation of China(Nos.11574367 and 11874405);the National Key Research and Development Program of China(Nos.2016YFA0300600,2018YFA0704200,and 2019YFA0308000);the Youth Innovation Promotion Association of CAS(Nos.2017013 and 2019007).

摘　　要：The mono layer WSe2 is in teresting and important for future application in nanoelectronics,spintronics and valleytronics devices,because it has the largest spin splitting and Ion gest valley coherence time among all the known monolayer transition-metal dichalcogenides(TMDs).Toobtain the large-area monolayer TMDs'crystal is the first step to manu facture scalable and high-performance electronic devices.In this letter,we have successfully fabricated millimeter-sized mono layer WSe2 single crystals with very high quality,based on our improved mecha nicalexfoliation method.With such superior samples,using standard high resolution angle-resolved photoemission spectroscopy,we didcomprehe nsive electronic band structure measurements on our mono layer WSe2.The overall band features point it to be a 1.2 eV direct bandgap semico nductor.Its spin splitting of the valence band at K point is found as 460 meV,which is 30 meV less than the corresponding band splitting in its bulk counterpart.The effective hole masses of valence bands are determined as 2.344 me atГ,and 0.529 me as well as 0.532 meat K for the upper and lower branch of splitting ban ds,respectively.And screening effect from substrate is shown to substa ntially impact onthe electronic properties.Our results provide importa nt insights into band structure engineering in mono layer TMDs.Our mono layer WSe2 crystals may constitute a valuable device platform.

关 键 词：TRANSITION-METAL DICHALCOGENIDES WSe2 MONOLAYER electronic structure angle-resolved PHOTOEMISSION spectroscopy 

分 类 号：O57[理学—粒子物理与原子核物理]