Abstract
We fabricated the stacked bilayer molybdenum disulfide (MoS2) by using reduced graphene oxide (rGO) as a spacer for increasing the optoelectronic properties of MoS2. The rGO can decrease the interlayer coupling between the stacked bilayer MoS2 and retain the direct band gap property of MoS2. We observed a twofold enhancement of the photoluminescence intensity of the stacked MoS2 bilayer. In the Raman scattering, we observed that the E12g and A1g modes of the stacked bilayer MoS2 with rGO were further shifted compared to monolayer MoS2, which is due to the van der Waals (vdW) interaction and the strain effect between the MoS2 and rGO layers. The findings of this study will expand the applicability of monolayer MoS2 for high-performance optoelectronic devices by enhancing the optical properties using a vdW spacer.
Highlights
The recent discovery of a new class of two-dimensional (2D) materials, transition metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2), has attracted attention because of their unique layer-dependent electrical and optical properties[1,2,3]
For the stacking of monolayer TMD, hexagonal boron nitride (h-BN) was introduced as the spacer for the TMD hetero-bilayer or homo-bilayer[16,17,18]. These results suggest that stacked TMD with the h-BN
The chemical vapor deposition (CVD)-grown monolayer MoS2 films were transferred onto the 300-nm-thick of SiO2/Si substrate using the conventional wet transfer method. (See Methods section for details) To prepare stacked bilayer MoS2, another CVD-grown monolayer MoS2 film was transferred onto the monolayer-MoS2/SiO2/Si template
Summary
The recent discovery of a new class of two-dimensional (2D) materials, transition metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2), has attracted attention because of their unique layer-dependent electrical and optical properties[1,2,3]. MoS2 possesses an indirect band gap of ~1.29 eV in bulk, but it becomes a direct optical band gap of ~1.90 eV in the monolayer and can affect the electronic and optical properties[4,5] These interesting features in MoS2 have opened up new possibilities for optoelectronic applications[6]. Few-layer MoS2 has an indirect band gap that limits its applicability for high-efficiency optoelectronic devices. For the stacking of monolayer TMD, hexagonal boron nitride (h-BN) was introduced as the spacer for the TMD hetero-bilayer or homo-bilayer[16,17,18] These results suggest that stacked TMD with the h-BN layer can retain the direct band gap feature of the monolayer TMD. We systematically investigated the origin the structural, chemical, and optical properties of the stacked MoS2 with/without spacer layer
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