Facile Resist‐Free Nanopatterning of Monolayers of MoS₂ by Focused Ion‐Beam Milling

Abstract

Nanopatterning of monolayers of transition metal dichalcogenides offers a new avenue for the creation of nanoscale light sources and their integration into hybrid nanophotonic systems. Here, focused gallium ion‐beam milling is employed as a resist‐free and simple nanofabrication approach to pattern MoS2 monolayers grown by chemical vapor deposition into nanoribbons. Using photoluminescence (PL), Raman, and valley polarization spectroscopy, it is investigated how the optoelectronic properties of the MoS2 monolayers are affected by the nanopatterning as a function of the ion fluence used for milling. Characteristic spectral shifts in the Raman and PL peaks are observed, which are indicative of a release of strain in patterned MoS2 monolayers as compared to the as‐grown monolayers. Furthermore, while the total PL signal is reduced in the patterned monolayers, using circular‐polarization‐resolved cryogenic PL spectroscopy it is shown that the valley polarization is well preserved for monolayers patterned within an optimal ion‐fluence range. The results and in particular the observed robustness of the valley polarization indicate that focused ion‐beam nanopatterned MoS2 monolayers are interesting candidates for their integration into hybrid quantum systems consisting of designed photonic nanostructures and precisely placed nanoscale excitonic light sources.

Engineering Optically Active Defects in Hexagonal Boron Nitride Using Focused Ion Beam and Water

“…Focused ion beam (FIB) seems an especially appealing technique for the generation of optically active defects in vdW materials due to its versatility, high resolution, ease of use, and scalability. Notably, FIB has found widespread use for patterning of 2D materials as a resist-free method, , mitigating omnipresent polymer contamination of the patterned material. And the emergence of commercially available plasma FIB (PFIB) machines, employing ions of inert gases, such as argon and xenon, instead of liquid metals, has solved the long-standing problem of sample contamination by gallium ions in traditional FIB systems. , Nevertheless, while deterministic defect generation in hBN using FIB has been recently demonstrated, , achieving submicron spatial accuracy, a clear understanding of the FIB irradiation effects and the formation of defect sites in hBN is lacking.…”

Resonance Coupling in Si@WS2Core-Ω Shell Nanostructure

“…For example, the WS 2 @Fe 3 O 4 nanocomposites [ 27 ] can be used for imaging and therapy functionalities. At K and K’ points of hexagonal Brillouin zones, the monolayer WS 2 with direct bandgap can realize the 2PA process [ 28 , 29 ]. The metal substrates could enhance the resonance coupling of the hybrid system [ 30 ].…”

Broadband Optical Constants and Nonlinear Properties of SnS2 and SnSe2

“…Van der Waals materials have emerged as a promising building block for next-generation optical and electronic devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Their planar structure [ 9 , 10 ] and the outstanding compatibility with existing manufacturing techniques [ 11 , 12 , 13 , 14 , 15 ] make such materials ideal for integration into modern industrial and scientific devices. Among layered materials, graphene [ 16 ], MoS 2 [ 17 ], and hBN [ 18 ] have received the most attention, as they were the first [ 19 , 20 , 21 ] to catch researchers’ interest during the “two-dimensional” revolution [ 22 ] in material science.…”