Journal
NANOTECHNOLOGY
Volume 31, Issue 29, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/1361-6528/ab87cd
Keywords
tungsten selenide; p-doped; molybdenum ditelluride; heterojunction; photodetector
Funding
- National Natural Science Foundation of China [61774042, 61774040]
- Shanghai Municipal Natural Science Foundation [16ZR1402500, 17ZR1446500, 17ZR1446600]
- National Young 1000 Talent Plan of China
- 'First-Class Construction' project of Fudan University [XM03170477]
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Van der Waals heterostructures (vdWHs) based on two-dimensional (2D) materials are being studied extensively for their prospective applications in photodetectors. As the pristine WSe2/MoTe2 heterostructure is a type I (straddling gap) structure, it cannot be used as a photovoltaic device theoretically, although both WSe2 and MoTe2 have excellent photoelectric properties. The Fermi level of p-doped WSe2 is close to its valence band. The p-doped WSe2/MoTe2 heterostructure can perform as a photovoltaic device because a built-in electric field appears at the interface between MoTe2 and p-doped WSe2. Here, a 633 nm laser was used for scanning the surface of WSe2 in order to obtain the p-doped WSe2. x-ray photoelectron spectroscopy (XPS) and electrical measurements verified that p-type doping in WSe2 is produced through laser treatment. The p-type doping in WSe2 includes substoichiometric WOx and nonstoichiometric WSex. A photovoltaic device using p-doped WSe2 and MoTe2 was successfully fabricated. The band structure, light-matter reactions, and carrier-transport in the p-doped WSe2/MoTe2 heterojunction were analyzed. The results showed that this photodetector has an on/off ratio of & x224d;10(4), dark current of & x224d;1 pA, and response time of 72 mu s under the illumination of 633 nm laser at zero bias (V-ds = 0 V). The proposed p-doping method may provide a new approach to improve the performance of nanoscale optoelectronic devices.
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