单层
X射线光电子能谱
兴奋剂
材料科学
外延
扫描隧道光谱
扫描隧道显微镜
费米能级
光电发射光谱学
光谱学
半导体
带隙
凝聚态物理
电子
纳米技术
光电子学
核磁共振
图层(电子)
物理
量子力学
作者
Yipu Xia,Bo Wang,Junqiu Zhang,Yue Feng,Bin Li,Xibiao Ren,Hao Tian,Jin-Peng Xu,Wingkin Ho,Hu Xu,Chang Liu,Chuanhong Jin,Maohai Xie
出处
期刊:2D materials
[IOP Publishing]
日期:2018-08-20
卷期号:5 (4): 041005-041005
被引量:17
标识
DOI:10.1088/2053-1583/aadb5c
摘要
Many transition-metal dichalcogenides, such as MoSe2, are direct-gap semiconductors at monolayer thickness, which hold potentials in nano-electronics, optoelectronics, and some new concept spin- and valley-electronic applications. For device application, however, controllable doping of the materials is essential. Here we report hole doping of epitaxial MoSe2 by nitrogen (N) plasma treatment with the aim of understanding the defect structure and its electronic characteristics. Examinations by annular dark field scanning transmission electron microscopy clearly reveal substitutional doping of N by replacing Se atoms in MoSe2 monolayer upon N-plasma treatment, though creation of Se vacancies are also possible. Interestingly, we note an unexpectedly high concentration of 'dual defects', where both Se atoms in the top and bottom Se layers of MoSe2 at the same lattice site are substituted by N and/or become vacant, suggesting a catalytic effect of defect formation. X-ray photoelectron spectroscopy and electron energy loss spectroscopy confirm the presence of N–Mo bonds. Photoemission spectroscopy reveals an impurity band as well as the Fermi level shift, confirming the p-type doping effect in MoSe2 monolayer by N-plasma treatment. Consistent with the PES results, scanning tunneling spectroscopy measurement also reveal defect states peaked at 0.6–0.7 eV above the valance band maximum. The effectiveness of N-doping is discussed.
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