Confined exciton photoluminescence in 2D transition metal dichalcogenide architectures from nano-strained regions revealed by scanning transmission electron microscopy

Assemblies comprised of materials with different dimensionalities can yield exceptional and highly tunable properties provided that the size, structure, and interfacial interaction between the constituents is precisely controlled. Here we fabricate a mixed-dimensional assembly by ‘draping’ CVD-grown 2D MoSe₂ monolayers over single-crystal silicon nanowires (NW), and by this process generate an extended region of localized strain in the monolayer along the edges of the NW. Near-field optical characterization reveals a photoluminescence (PL) peak characteristic of emission (at 1.57 eV) from the MoSe₂ A-exciton in regions away from this strained area. Notably, we uncover an anomalous PL feature at 1.38 eV coincident with the strained area of the 2D MoSe₂-NW assembly. To better understand the origin of this anomalous peak, we use aberration-corrected HAADF-STEM to determine the atomic structure of the MoSe₂ lattice near the Si NW.