Journal
ACS NANO
Volume 12, Issue 10, Pages 10529-10536Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b06503
Keywords
TMDCs; localized states; heterostructure; photodetector; ion irradiation
Categories
Funding
- National Natural Science Foundation of China [11535008, 11775136]
- Shandong University [2015WLJH20]
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Point defects in 2D materials block in-plane charge transport, which incurs negative effects on the photoresponse of 2D monolayer materials. In contrast to in-plane charge transport, we show that out-of-plane charge transport in 2D materials can be enhanced through controllable formation of point defects, thus enhancing the photoresponse of a vertical heterostructure. Graphene and WSe2 monolayers were stacked together to construct a vertical heterostructure (W/G). Se point defects were artificially formed on the top atomic layer of WSe2 with controllable density via Ga ion irradiation. The interlayer charge transport in the W/G heterostructure was detected with femtosecond optical probe-pump measurements and photoelectric detection. Our experiments show that point defects can be used to provide higher transfer rate for out-of-plane charge transport and more electronic states for photoexcitation, leading to enhanced photoinduced interlayer charge transfer from WSe2 to graphene. Based on this feature, a photodetector based on W/G modified by point defects is proposed and implemented, exhibiting a fast photoresponsivity (similar to 0.6 ms) (2 orders of magnitude larger than the photoresponse in pristine W/G). This work demonstrates that out-of-plane charge transport is enhanced by the presence of point defects and illustrates an efficient method to optimize the performance of photoelectric devices based on vertical heterostructures.
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