One-Dimensional Crystallographic Etching of Few-Layer WS$_2$

TL;DR

This paper introduces a novel technique for etching one-dimensional nanotrenches in few-layer WS$_2$ using in-situ generated droplets, enabling the creation of 1D nanochannels with enhanced optical properties for advanced photonic applications.

Contribution

The study presents a new droplet migration-based etching method to fabricate 1D nanotrenches in WS$_2$, allowing controlled top-down and bottom-up nanostructure formation.

Findings

Successful fabrication of 1D WS$_2$ nanotrenches with enhanced photoluminescence.

Switchable etching and growth modes via sulfur supply manipulation.

Potential for creating 1D-2D mixed-dimensional TMDC nanostructures.

Abstract

Layer number-dependent band structures and symmetry are vital for the electrical and optical characteristics of two-dimensional (2D) transition metal dichalcogenides (TMDCs). Harvesting 2D TMDCs with tunable thickness and properties can be achieved through top-down etching and bottom-up growth strategies. In this study, we report a pioneering technique that utilizes the migration of in-situ generated Na-W-S-O droplets to etch out one-dimensional (1D) nanotrenches in few-layer WS$_2$. 1D WS$_2$ nanotrenches were successfully fabricated on the optically inert bilayer WS$_2$, showing pronounced photoluminescence and second harmonic generation signals. Additionally, we demonstrate the modulation of inkjet-printed Na$_2$WO$_4$-Na$_2$SO$_4$ particles to switch between the etching and growth modes by manipulating the sulfur supply. This versatile approach enables the creation of 1D nanochannels on 2D TMDCs. Our research presents exciting prospects for the top-down and bottom-up fabrication of 1D-2D mixed-dimensional TMDC nanostructures, expanding their use for photonic and optoelectronic applications.