Photoluminescent Arrays of Nanopatterned Monolayer MoS₂

Abstract

Monolayer 2D MoS 2 grown by chemical vapor deposition is nanopatterned into nanodots, nanorods, and hexagonal nanomesh using block copolymer (BCP) lithography. The detailed atomic structure and nanoscale geometry of the nanopatterned MoS 2 show features down to 4 nm with nonfaceted etching profiles defined by the BCP mask. Atomic resolution annular dark field scanning transmission electron microscopy reveals the nanopatterned MoS 2 has minimal large-scale crystalline defects and enables the edge density to be measured for each nanoscale pattern geometry. Photoluminescence spectroscopy of nanodots, nanorods, and nanomesh areas shows strain-dependent spectral shifts up to 15 nm, as well as reduction in the PL efficiency as the edge density increases. Raman spectroscopy shows mode stiffening, confirming the release of strain when it is nanopatterned by BCP lithography. These results show that small nanodots (≈19 nm) of MoS 2 2D monolayers still exhibit strong direct band gap photoluminescence (PL), but have PL quenching compared to pristine material from the edge states. This information provides important insights into the structure-PL property correlations of sub-20 nm MoS 2 structures that have potential in future applications of 2D electronics, optoelectronics, and photonics.

Emerging nanofabrication and quantum confinement techniques for 2D materials beyond graphene

“…Additionally, RIE processes are largely anisotropic in nature. Some popular plasma species for etching TMDCs include O 2 , 41-44 CF 4 , 41,45 and SF 6 . 46 Fluorinated plasma species (and other halogen species) are popular etching plasmas due to their high electronegatively.…”

“…BCP lithography with an oxygen plasma etch has been used to pattern MoS 2 with features down to 4 nm. 41 This technique can yield arrays of nanodots, nanorods, and nanomeshes. In fact, BCP patterning has been used to fabricate sub-10 nm MoS 2 field-effect transistor channels (which will be further highlighted in the emerging devices section).…”

Multifunctional Structured Platforms: From Patterning of Polymer-Based Films to Their Subsequent Filling with Various Nanomaterials

“…The transfer of (flexible [ 237 ]) surface relief patterns on graphene [ 234 , 237 ] or other solid, often functionalized [ 239 ], substrates [ 206 , 240 ] can be done by employing additional etching or infiltration [ 233 , 238 , 241 ] procedures, which is followed by the controlled deposition of thin films of various materials [ 205 , 241 , 242 ], including metals [ 243 ] and metal oxides [ 244 ]. Examples of etching procedures include UV ozone [ 243 ], oxygen [ 241 , 243 ], nitrogen [ 241 ], or other types [ 239 , 241 ] of plasma etching, CO 2 and Cl 2 /O 2 reactive ion etching [ 205 ], etching in alkaline solutions [ 204 ]), etc.…”

Transition Metal Dichalcogenides for Sensing and Oncotherapy: Status, Challenges, and Perspective

“…Bottomup strategies for synthesizing TMDCs nanodots include hydrothermal/solvothermal reaction [39] and CVD. [40] TMDC-based nanofibers and nanorods are generally composite materials. The layered structure TMDCs are easy to manipulate into 2D films, nanosheets, and nanodots.…”