Enhanced Photoluminescence of Solution-Exfoliated Transition Metal Dichalcogenides by Laser Etching

Abstract

Using a conventional Raman experimental apparatus, we demonstrate that the photoluminescent (PL) yield from ultrasonication-exfoliated transition metal dichalcogenides (TMDs) (MoS 2 and WS 2 ) can be increased by up to 8-fold by means of a laser etching procedure. This laser etching process allows us to controllably pattern and reduce the number of layers of the solution-exfoliated material, overcoming the key drawback to solvent-based exfoliation of two-dimensional (2D) semiconducting materials for applications in optoelectronics. The successful laser thinning of the exfoliated 2D crystals was investigated systematically by changes in both Raman and PL spectra. A simple proof-of-principle of the scalability of this laser etching technique for solution-exfoliated TMD crystals was also demonstrated. As well as being applicable for individual materials, it is also possible to use this simple laser etching technique to investigate the structure of solution-generated van der Waals heterostructures, consisting of layers of both MoS 2 and WS 2 .

Solution-Based Synthesis of Few-Layer WS2 Large Area Continuous Films for Electronic Applications

“…Moreover, all peaks become narrower after the second annealing step. The most dramatic change was with the peak labelled LA (M)-TA(M) 31 where its FWHM was reduced from 63.4 cm −1 in the first annealing step to 24.4 cm −1 in the second annealing step for SiO 2 /Si and from 51 cm −1 to 28 cm −1 for sapphire. Additional peaks that correspond to 2LA (K) mode 32 are also apparent at 385.2 cm −1 and 387.7 cm −1 for SiO 2 /Si and sapphire respectively, which did not exist after the first annealing step.…”

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

“…Focused lasers have been used to etch MoS 2 and WS 2 in a controllable manner with the likely mechanism being thermal sublimation or oxidation/evaporation in ambient conditions. [133][134][135] This technique can be used to etch features such as nanoribbons into MoS 2 . 133 Voids formed from the etching process also exhibited hexagonal geometry, thus revealing the orientation of the lattice (Fig.…”

Laser printed two-dimensional transition metal dichalcogenides

“…It is also important to note that exploring the parameter space of direct laser synthesis will allow thickness control of the MoS 2 or WS 2 via sublimation of the topmost layers 23 , 26 ; improve the crystallinity of the TMDCs 32 , 33 ; and affect the amount of the oxide content in the structures 37 , 41 , 42 .…”