Laser-thinning of MoS2: on demand generation of a single-layer semiconductor

TL;DR

This paper introduces a laser-based technique to precisely thin multilayer MoS2 down to single layers with controlled shape and size, enabling improved fabrication of 2D semiconductors for electronic applications.

Contribution

The authors develop a laser-thinning method for deterministic creation of single-layer MoS2 with arbitrary shapes and nanoscale features.

Findings

Single-layer MoS2 produced with optical and electronic properties comparable to exfoliated samples

Feature sizes as small as 200 nm achievable

Controlled thinning process enhances device fabrication potential

Abstract

Single-layer MoS2 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 MoS2 is an indirect bandgap semiconductor similar to silicon, with a gap of 1.2 eV, and therefore deterministic preparation of single MoS2 layers is a crucial step towards exploiting the large direct bandgap of monolayer MoS2 in electronic, optoelectronic, and photovoltaic applications. Although mechanical and chemical exfoliation methods can be used to obtain high quality MoS2 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 MoS2 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 MoS2 single layers.