Abstract

Atomically sharp edges are essential for future high-index nanophotonic structures, yet conventional lithography and dry etching methods inevitably introduce edge roughness that limits optical confinement and reproducibility. Recently, anisotropic wet etching of multilayer van der Waals crystals, such as transition metal dichalcogenides (TMDs), has enabled crystallographically defined, atomically sharp zigzag edges, thereby eliminating the edge-roughness problem. However, the process is intrinsically limited to confined geometries such as isolated triangular or hexagonal features dictated by crystal stacking symmetry. Here, we demonstrate a lithography-guided anisotropic etching framework that drives TMDs etching beyond isolated confined geometries by enforcing controlled interaction of neighboring etched nanoholes regions. In multilayer 2H-WS2, merging of anisotropic etch fronts enables sustained long-range propagation of zigzag facets, introducing a previously inaccessible 180° edge alignment and a crystallographically defined design space combining 120° and 180° junctions. Using this approach, we fabricate proof-of-principle extended nanophotonic structures with ultrasharp sidewalls (approaching atomic precision), including sub-100-nm-gap one-dimensional gratings, waveguides, defect-engineered photonic cavities, angle-programmed photonic lattices, and radially patterned diffractive zone plates. Beyond structural characterization, back-focal-plane reflection spectroscopy of atomically sharp 1D periodic 2H-WS₂ gratings demonstrates their photonic functionality, revealing symmetry-protected bound states in the continuum (SP-BICs) and strong exciton–photon coupling in multilayer WS2. Finally, we fabricate ultrathin, ultranarrow, and ultralong nanoribbons with record-high aspect ratios. Together, these results demonstrate, to our knowledge for the first time, edge merging as a generic route to fabricate edge-defined, atomically sharp nanophotonic and nanoelectronic architectures in layered van der Waals platforms.

Abstract

Atomically sharp edges are essential for future high-index nanophotonic structures, yet conventional lithography and dry etching methods inevitably introduce edge roughness that limits optical confinement and reproducibility. Recently, anisotropic wet etching of multilayer van der Waals crystals, such as transition metal dichalcogenides (TMDs), has enabled crystallographically defined, atomically sharp zigzag edges, thereby eliminating the edge-roughness problem. However, the process is intrinsically limited to confined geometries such as isolated triangular or hexagonal features dictated by crystal stacking symmetry. Here, we demonstrate a lithography-guided anisotropic etching framework that drives TMDs etching beyond isolated confined geometries by enforcing controlled interaction of neighboring etched nanoholes regions. In multilayer 2H-WS2, merging of anisotropic etch fronts enables sustained long-range propagation of zigzag facets, introducing a previously inaccessible 180° edge alignment and a crystallographically defined design space combining 120° and 180° junctions. Using this approach, we fabricate proof-of-principle extended nanophotonic structures with ultrasharp sidewalls (approaching atomic precision), including sub-100-nm-gap one-dimensional gratings, waveguides, defect-engineered photonic cavities, angle-programmed photonic lattices, and radially patterned diffractive zone plates. Beyond structural characterization, back-focal-plane reflection spectroscopy of atomically sharp 1D periodic 2H-WS₂ gratings demonstrates their photonic functionality, revealing symmetry-protected bound states in the continuum (SP-BICs) and strong exciton–photon coupling in multilayer WS2. Finally, we fabricate ultrathin, ultranarrow, and ultralong nanoribbons with record-high aspect ratios. Together, these results demonstrate, to our knowledge for the first time, edge merging as a generic route to fabricate edge-defined, atomically sharp nanophotonic and nanoelectronic architectures in layered van der Waals platforms.

Abstract

Atomically sharp edges are essential for future high-index nanophotonic structures, yet conventional lithography and dry etching methods inevitably introduce edge roughness that limits optical confinement and reproducibility. Recently, anisotropic wet etching of multilayer van der Waals crystals, such as transition metal dichalcogenides (TMDs), has enabled crystallographically defined, atomically sharp zigzag edges, thereby eliminating the edge-roughness problem. However, the process is intrinsically limited to confined geometries such as isolated triangular or hexagonal features dictated by crystal stacking symmetry. Here, we demonstrate a lithography-guided anisotropic etching framework that drives TMDs etching beyond isolated confined geometries by enforcing controlled interaction of neighboring etched nanoholes regions. In multilayer 2H-WS2, merging of anisotropic etch fronts enables sustained long-range propagation of zigzag facets, introducing a previously inaccessible 180° edge alignment and a crystallographically defined design space combining 120° and 180° junctions. Using this approach, we fabricate proof-of-principle extended nanophotonic structures with ultrasharp sidewalls (approaching atomic precision), including sub-100-nm-gap one-dimensional gratings, waveguides, defect-engineered photonic cavities, angle-programmed photonic lattices, and radially patterned diffractive zone plates. Beyond structural characterization, back-focal-plane reflection spectroscopy of atomically sharp 1D periodic 2H-WS₂ gratings demonstrates their photonic functionality, revealing symmetry-protected bound states in the continuum (SP-BICs) and strong exciton–photon coupling in multilayer WS2. Finally, we fabricate ultrathin, ultranarrow, and ultralong nanoribbons with record-high aspect ratios. Together, these results demonstrate, to our knowledge for the first time, edge merging as a generic route to fabricate edge-defined, atomically sharp nanophotonic and nanoelectronic architectures in layered van der Waals platforms.

Abstract

Atomically sharp edges are essential for future high-index nanophotonic structures, yet conventional lithography and dry etching methods inevitably introduce edge roughness that limits optical confinement and reproducibility. Recently, anisotropic wet etching of multilayer van der Waals crystals, such as transition metal dichalcogenides (TMDs), has enabled crystallographically defined, atomically sharp zigzag edges, thereby eliminating the edge-roughness problem. However, the process is intrinsically limited to confined geometries such as isolated triangular or hexagonal features dictated by crystal stacking symmetry. Here, we demonstrate a lithography-guided anisotropic etching framework that drives TMDs etching beyond isolated confined geometries by enforcing controlled interaction of neighboring etched nanoholes regions. In multilayer 2H-WS2, merging of anisotropic etch fronts enables sustained long-range propagation of zigzag facets, introducing a previously inaccessible 180° edge alignment and a crystallographically defined design space combining 120° and 180° junctions. Using this approach, we fabricate proof-of-principle extended nanophotonic structures with ultrasharp sidewalls (approaching atomic precision), including sub-100-nm-gap one-dimensional gratings, waveguides, defect-engineered photonic cavities, angle-programmed photonic lattices, and radially patterned diffractive zone plates. Beyond structural characterization, back-focal-plane reflection spectroscopy of atomically sharp 1D periodic 2H-WS₂ gratings demonstrates their photonic functionality, revealing symmetry-protected bound states in the continuum (SP-BICs) and strong exciton–photon coupling in multilayer WS2. Finally, we fabricate ultrathin, ultranarrow, and ultralong nanoribbons with record-high aspect ratios. Together, these results demonstrate, to our knowledge for the first time, edge merging as a generic route to fabricate edge-defined, atomically sharp nanophotonic and nanoelectronic architectures in layered van der Waals platforms.