Position‐Controlled Fabrication of Vertically Aligned Mo/MoS₂ Core–Shell Nanopillar Arrays

Abstract

The fabrication of 2D materials, such as transition metal dichalcogenides (TMDs), in geometries beyond the standard platelet‐like configuration exhibits significant challenges which severely limit the range of available morphologies. These challenges arise due to the anisotropic character of their bonding van der Waals out‐of‐plane while covalent in‐plane. Furthermore, industrial applications based on TMD nanostructures with non‐standard morphologies require full control on the size‐, morphology‐, and position on the wafer scale. Such a precise control remains an open problem of which solution would lead to the opening of novel directions in terms of optoelectronic applications. Here, a novel strategy to fabricate position‐controlled Mo/MoS2 core–shell nanopillars (NPs) is reported on. Metal‐Mo NPs are first patterned on a silicon wafer. These Mo NPs are then used as scaffolds for the synthesis of Mo/MoS2 core/shell NPs by exposing them to a rich sulfur environment. Transmission electron microscopy analysis reveals the core/shell nature of the NPs. It is demonstrated that individual Mo/MoS2 NPs exhibits significant nonlinear optical processes driven by the MoS2 shell, realizing a precise localization of the nonlinear signal. These results represent an important step towards realizing 1D TMD‐based nanostructures as building blocks of a new generation of nanophotonic devices.

Aqueous Topological Synthesis of Au@semiconductor Core–Shell Nanocrystals with Morphology and Composition Engineering

“…Colloidal core–shell nanocrystals (C–S NCs), especially the noble metal@semiconductor (NMS) C–S NCs with plasmon-exciton coupling effect, are an essential class of materials due to their tunable optical and electrical properties. − NMS C–S NCs have kept the controllable localized surface plasmon resonance (LSPR) effect from the noble metal, the widely tunable absorption benefiting from various compositions, and the maximum degree of functional coupling corresponding to the most extensive contact areas. − In the past decades, many strategies have been utilized to synthesize NMS C–S NCs, such as vapor deposition, molecular beam epitaxy, and colloidal epitaxial growth. − Beyond this, it is desirable to assume a general strategy with not only flexible morphology and composition engineering but also hydrophilic surface chemistry.…”

About synthesis mechanism of periodic oxide nanocrystallites on surface of single-crystal InP

“…As a rule, the only problem when such heterostructures are formed is the mismatch of the crystal lattices, which causes a large number of stress states at the boundary of two heterostructure components [36]. On the other hand, such situation can be effectively used when structures with non-standard morphology are formed [37,38]. In this case, the defects of the output semiconductor (substrate) are the source of the nanostructure on the surface [39].…”

Magnetic Field Alignment and Optical Anisotropy of MoS2 Nanosheets Dispersed in a Liquid Crystal Polymer

“…Optical anisotropy in MoS 2 has been experimentally explored by near-field measurements that have resolved differences in the Raman response , and dielectric constants of nanosheet basal planes and edges. , The anisotropy stems from the inherent 2D morphology of the MoS 2 nanosheets, which has been previously observed by aligning the nanosheets in a parallel or transverse configuration with respect to the probing beam. − …”

“…Despite the impetus to elucidate the anisotropic optical properties in few-layer MoS 2 , current methods to do so are lacking in their ability to robustly control few-layer MoS 2 nanosheet orientation, inhibiting the opportunities to devise technologies that harness the difference in optical properties parallel and transverse to the nanosheets surface normal or to further explore and study the anisotropy in detail. As highlighted above, studies of anisotropic effects in MoS 2 rely on orientation control of grown or patterned bulk MoS 2 films or particles, which are then studied by using traditional spectroscopic characterization techniques, ,− ,, but disregard few-layer nanosheets, whose anisotropic characteristics may vary considerably from the bulk material. Conversely, the study of individually exfoliated MoS 2 nanosheets has relied on near-field techniques that are challenging to leverage, particularly in statistically relevant scenarios. ,, Hence, the ability to suspend individual nanosheets and control their orientation in a suitable dielectric medium would enable important studies of PL and other optical anisotropies in MoS 2 with a versatility that has thus far been lacking.…”