Research Article


2016, 9(12): 3622–3631


Defects as a factor limiting carrier mobility in WSe2: A spectroscopic investigation

Zhangting Wu1, Zhongzhong Luo2, Yuting Shen3, Weiwei Zhao4, Wenhui Wang1, Haiyan Nan1, Xitao Guo1, Litao Sun3, Xinran Wang2, Yumeng You5 (*), and Zhenhua Ni1 (*)

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1 Department of Physics and Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
2 National Laboratory of Solid State Microstructure, School of Electronic Science and Engineering, National Center of Microstructures and Quantum Manipulation, Nanjing University, Nanjing 210093, China
3 SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096, China
4 Jiangsu Key Laboratory for Design and Fabrication of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189, China
5 Ordered Matter Science Research Center, Southeast University, Nanjing 211189, China

Keywords: two-dimensional materials, tungsten diselenide, structural defects, photoluminescence spectroscopy, mobility
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ABSTRACT The electrical performance of two-dimensional transition metal dichalcogenides (TMDs) is strongly affected by the number of structural defects. In this work, we provide an optical spectroscopic characterization approach to correlate the number of structural defects and the electrical performance of WSe2 devices. Low-temperature photoluminescence (PL) spectra of electron-beam-lithographyprocessed WSe2 exhibit a clear defect-induced PL emission due to excitons bound to defects, which would strongly degrade the electrical performance. By adopting an electron-beam-free transfer-electrode technique, we successfully prepared a backgated WSe2 device containing a limited amount of defects. A maximum hole mobility of approximately 200 cm2·V–1·s–1 was achieved because of the reduced scattering sources, which is the highest reported value for this type of device. This work provides not only a versatile and nondestructive method to monitor the defects in TMDs but also a new route to approach the room-temperature phonon-limited mobility in high-performance TMD devices.
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Defects as a factor limiting carrier mobility in WSe2: A spectroscopic investigation. Nano Res. 2016, 9(12): 3622–3631

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