Monolayer transition metal dichalcogenides (TMDs) are promising for optoelectronics because of their high optical quantum yield and strong light-matter interaction. In particular, the van der Waals (vdW) heterostructures consisting of monolayer TMDs sandwiched by large gap hexagonal boron nitride have shown great potential for novel optoelectronic devices. However, a complicated stacking process limits scalability and practical applications. Furthermore, even though lots of efforts, such as fabrication of vdW heterointerfaces, modification of the surface, and structural phase transition, have been devoted to preserve or modulate the properties of TMDs, high environmental sensitivity and damage-prone characteristics of TMDs make it difficult to achieve a controllable technique for surface/interface engineering. Here, we demonstrate a novel way to fabricate multiple two-dimensional (2D) vdW heterostructures consisting of alternately stacked MoS2 and MoOx with enhanced photoluminescence (PL). We directly oxidized multilayer MoS2 to a MoOx/1 L-MoS2 heterostructure with atomic layer precision through a customized oxygen plasma system. The monolayer MoS2 covered by MoOx showed an enhanced PL intensity 3.2 and 6.5 times higher in average than the as-exfoliated 1 L- and 2 L-MoS2 because of preserved crystallinity and compensated dedoping by MoOx. By using layer-by-layer oxidation and transfer processes, we fabricated the heterostructures of MoOx/MoS2/MoOx/MoS2, where the MoS2 monolayers are separated by MoOx. The heterostructures showed the multiplied PL intensity as the number of embedded MoS2 layers increases because of suppression of the nonradiative trion formation and interlayer decoupling between stacked MoS2 layers. Our work shows a novel way toward the fabrication of 2D material-based multiple vdW heterostructures and our layer-by-layer oxidation process is beneficial for the fabrication of high performance 2D optoelectronic devices.
Bibliographical noteFunding Information:
This work was supported by Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20173010013340), National Research Foundation of Korea (NRF) grant funded by the Korean government (2018M3D1A1058793, 2017R1A5A1014862, SRC program: vdWMRC center, and NRF-2020R1A2c2009389), Creative-Pioneering Researchers Program through Seoul National University (SNU), KU-KIST school project, and NSF MRSEC award number DMR-1720633. The work was carried out in part in the Materials Research Laboratory Central Facilities at the University of Illinois. H.Y.J. acknowledges support from the Creative Materials Discovery Program through the National Research Foundation of Korea (NRF-2016M3D1A1900035).
© 2020 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)