Atomic-Scale Moiré and Electronic Structure Analysis of Twisted Epitaxial MoS2-Au-MoS2 Heterostructures.

Twisted epitaxy enables precise orientation control of nanostructures confined within van der Waals (vdW) gaps. Here, we investigate the moiré and electronic structure of a representative twisted epitaxial system, where Au nanodiscs are grown inside twisted bilayer MoS2 with a 6° interlayer twist, inducing a 3° symmetrical misalignment of Au relative to each MoS2 layer (MoS2-Au-MoS2). Using multislice electron ptychography (MEP), we resolve the three-dimensional "moiré-of-moirés" structure of MoS2-Au-MoS2 with atomic resolution. Electron energy loss spectroscopy (EELS) shows that MoS2 encapsulation significantly reduces the plasmon energy of Au nanodiscs compared with their unencapsulated counterparts. Furthermore, first-principles calculations reveal that Au insertion alters the electronic band alignment near the Fermi level of bilayer MoS2. Our results introduce a twisted MoS2-Au-MoS2 heterostructure as a structurally and electronically rich material system and establish twisted epitaxy as a new strategy for moiré engineering and the synthesis of 2D-confined materials with tunable optoelectronic properties.