Thermally Activated Gold‐Mediated Transition Metal Dichalcogenide Exfoliation and a Unique Gold‐Mediated Transfer

Giovanni Ligorio,Max Heyl,Emil J W List-Kratochvil,David Burmeister,Thorsten Schultz,Norbert Koch,Sebastian Pallasch

doi:10.1002/pssr.202000408

Abstract

Layered materials like transition metal dichalcogenides (TMDCs) enable exciting new physics in their 2D limit. Combined with successful demonstrations of 2D transistors and devices, the need for high‐quality large‐scale monolayers increases. In this light, scalable gold‐mediated exfoliations attract broad attention to supersede the traditional scotch tape method as a means for high‐quality materials. Gold proved to be suitably adhesive for the exfoliation of several 2D materials, including TMDCs. Previously reported methods rely on a simple press and peel mechanism. However, herein, a gold‐mediated exfoliation enabled by low‐temperature annealing is presented for the first time. This simple modification potentially increases the range of external conditions under which gold‐mediated exfoliations operate in a robust manner. The exfoliation achieves scaling with parent crystal areas, rendering it on par with previously reported methods. On top of that, a unique gold‐mediated transfer concept is introduced, where gold is repurposed as a metallic (polymer‐free) transfer membrane. The transfer allows the deterministic and clean relocation of the exfoliated monolayers onto technologically relevant substrates like SiO2/Si. The process is benchmarked using MoS2 as the prototypical TMDC and monolayer areas up to ≈80 mm2 are successfully exfoliated and transferred.

Highlights

Which fostered the development of different techniques ranging from bottom-up approaches like chemical vapor deposition (CVD) and molecular-beam epitaxy (MBE)[8] to top-down routes via mechanical materials, including Transition metal dichalcogenides (TMDCs)
Gold pounds where layers are held together by weak van der Waals interactions and can be cleaved with ease, enabling the exfoliation of a single layer by means of physically thinning down the crystal.[1,2]. This transition from 3D to 2D[2,3] is accompanied has been investigated as an exfoliation substrate and provides the needed adhesive forces via strong vdW[11] or “covalent-like quasibonding” (CLQB)[12] interactions with layered materials
Template-stripped gold substrates acted as ideal exfoliation substrates to yield large-area and highly continuous MoS2

Summary

Introduction

Which fostered the development of different techniques ranging from bottom-up approaches like chemical vapor deposition (CVD) and molecular-beam epitaxy (MBE)[8] to top-down routes via mechanical materials, including TMDCs. Supporting Information),[11,12,13,14] rendering MoS2 a perfect TMDC prototype for benchmarking gold-assisted exfoliations.

Results

Conclusion