Laser-Thinning of MoS₂: On Demand Generation of a Single-Layer Semiconductor

Abstract

Single-layer MoS(2) is an attractive semiconducting analogue of graphene that combines high mechanical flexibility with a large direct bandgap of 1.8 eV. On the other hand, bulk MoS(2) is an indirect bandgap semiconductor similar to silicon, with a gap of 1.2 eV, and therefore deterministic preparation of single MoS(2) layers is a crucial step toward exploiting the large direct bandgap of monolayer MoS(2) in electronic, optoelectronic, and photovoltaic applications. Although mechanical and chemical exfoliation methods can be used to obtain high quality MoS(2) single layers, the lack of control in the thickness, shape, size, and position of the flakes limits their usefulness. Here we present a technique for controllably thinning multilayered MoS(2) down to a single-layer two-dimensional crystal using a laser. We generate single layers in arbitrary shapes and patterns with feature sizes down to 200 nm and show that the resulting two-dimensional crystals have optical and electronic properties comparable to that of pristine exfoliated MoS(2) single layers.

Plasma-assisted fabrication of monolayer phosphorene and its Raman characterization

“…It is therefore critical to find a simple and efficient method to fabricate monolayer phosphorene. Recently, it has been demonstrated that layer-by-layer thinning of multilayers of MoS2 under plasma or laser irradiation is an efficient approach to get monolayer MoS2 15,16 . Here, we demonstrate plasma thinning also works as an effective way to achieve monolayer phosphorene.…”

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

“…This method is not scalable, however, and does not allow systematic control of flake thickness and size. Recently, a focused laser spot has been used to thin MoS 2 down to monolayer thickness by thermal ablation with micrometre-scale resolution, but the requirement for laser raster scanning makes it challenging for scale-up 42 .…”

Universal ac conduction in large area atomic layers of CVD-grown MoS2

“…Such observations, mostly on mechanically exfoliated layers of MoS 2 from single crystals, provided enough impetus to explore innovative methods for large-scale synthesis of atomically thin MoS 2 layers [3,[11][12][13][14][15]. Among these, liquid phase exfoliation [3,11], laser thinning [12], as well as the chemical vapor deposition (CVD) method [13][14][15] are now being utilized to synthesize large-scale area MoS 2 layers.…”

“…Among these, liquid phase exfoliation [3,11], laser thinning [12], as well as the chemical vapor deposition (CVD) method [13][14][15] are now being utilized to synthesize large-scale area MoS 2 layers. However, the materials produced using these techniques are, in general, susceptible to structural disorder [16,17].…”