Wet chemical thinning of molybdenum disulfide down to its monolayer

Abstract

We report on the preparation of mono- and bi-layer molybdenum disulfide (MoS2) from a bulk crystal by facile wet chemical etching. We show that concentrated nitric acid (HNO3) effectively etches thin MoS2 crystals from their edges via formation of MoO3. Interestingly, etching of thin crystals on a substrate leaves behind unreacted mono- and bilayer sheets. The flakes obtained by chemical etching exhibit electronic quality comparable to that of mechanically exfoliated counterparts. Our findings indicate that the self-limiting chemical etching is a promising top-down route to preparing atomically thin crystals from bulk layer compounds.

Chemical Patterning of High‐Mobility Semiconducting 2D Bi2O2Se Crystals for Integrated Optoelectronic Devices

“…To this end, great efforts have been devoted to developing effective dry‐etch approaches for patterning with excellent controllability, such as exemplified by focused ion beam etching, femtosecond laser etching, and reactive ion etching . In contrast to these relatively expensive and complicated dry etching techniques, wet chemical etching is a desirable way for its prominent advantages such as simple procedure, scalable production, well controllability, and low cost . However, it is difficult to achieve precision patterning and placement of novel 2D materials without inducing defects that are detrimental to the performance of integrated devices.…”

Topography preserved microwave plasma etching for top-down layer engineering in MoS2and other van der Waals materials

“…Methods utilizing material chemistry exploit either harsh chemicals 19 or reactive plasma environment, are material specific. [21][22][23]28 Physical etching involves high temperature annealing, 25,27 laser assisted thermal ablation 20 or plasma environments, 24,26,29 results in degraded electrical properties.…”

“…Postetch electrical characterization has not been performed in most cases, except for a few. 19,20,27 A generic topdown approach applicable to any vW material, scalable and compatible with the current fabrication technology, without compromising the electrical properties, would stride towards the realization of all 2D micrelectronics.…”

“…Though various etching schemes have been explored, [19][20][21][22][23][24][25][26][27][28][29] a scalable and controllable thickness reduction down to the mono-or few-layer regimes starting from arbitrary thickness and area has not been demonstrated. Methods utilizing material chemistry exploit either harsh chemicals 19 or reactive plasma environment, are material specific.…”

Hot‐wire vapor deposition of amorphous MoS2 thin films

“…In view of the above applications methods were developed for the deposition of single-layered films of MoS 2 spanning from microexfoliation of single crystals [16][17][18] to chemical vapor deposition (CVD) [19,20] and wet processes [21]. Also, methods have been elaborated to obtain single-layered films by chemical processing of thicker ones [22].…”