Enhanced Photoluminescence of Multiple Two-Dimensional van der Waals Heterostructures Fabricated by Layer-by-Layer Oxidation of MoS₂ (original) (raw)

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 MoS 2 and MoO x with enhanced photoluminescence (PL). We directly oxidized multilayer MoS 2 to a MoO x /1 L-MoS 2 heterostructure with atomic layer precision through a customized oxygen plasma system. The monolayer MoS 2 covered by MoO x showed an enhanced PL intensity 3.2 and 6.5 times higher in average than the as-exfoliated 1 L-and 2 L-MoS 2 because of preserved crystallinity and compensated dedoping by MoO x . By using layer-by-layer oxidation and transfer processes, we fabricated the heterostructures of MoO x /MoS 2 /MoO x /MoS 2 , where the MoS 2 monolayers are separated by MoO x . The heterostructures showed the multiplied PL intensity as the number of embedded MoS 2 layers increases because of suppression of the nonradiative trion formation and interlayer decoupling between stacked MoS 2 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.