Large-Area Electrodeposition of Few-Layer MoS₂ on Graphene for 2D Material Heterostructures

Abstract

Heterostructures involving two-dimensional (2D) transition metal dichalcogenides and other materials such as graphene have a strong potential to be the fundamental building block of many electronic and opto-electronic applications. The integration and scalable fabrication of such heterostructures is of essence in unleashing the potential of these materials in new technologies. For the first time, we demonstrate the growth of few-layer MoS2 films on graphene via non-aqueous electrodeposition. Through methods such as scanning and transmission electron microscopy, atomic force microscopy, Raman spectroscopy, energy and wavelength dispersive X-ray spectroscopies and X-ray photoelectron spectroscopy, we show that this deposition method can produce large-area MoS2 films with high quality and uniformity over graphene. We reveal the potential of these heterostructures by measuring the photo-induced current through the film. These results pave the way towards developing the electrodeposition method for the large-scale growth of heterostructures consisting of varying 2D materials for many applications.

Lateral Growth of MoS2 2D Material Semiconductors Over an Insulator Via Electrodeposition

“…In previous works, we characterized the material composition of MoS 2 films electrodeposited via similar electrochemical environments using wavelength dispersive X‐ray spectroscopy (WDX) and X‐ray photoelectron spectroscopy (XPS). [ 7,8 ] These results have shown that the Mo:S ratio is ≈1:2.…”

“…The electrodeposition experiments were performed in CH 2 Cl 2 solvent using [N n Bu 4 ] 2 [MoS 4 ], which was synthesized in‐house to function as a single source precursor, providing both the Mo and S. [ 7,8 ] In contrast to [NH 4 ] 2 [MoS 4 ], which has been used in aqueous solvents, [N n Bu 4 ] 2 [MoS 4 ] has excellent solubility in CH 2 Cl 2 . The electrodeposition solution also included [N n Bu 4 ]Cl as the supporting electrolyte and trimethylammonium chloride [NHMe 3 ]Cl as the proton source, which is necessary to remove the excess S during deposition of MoS 2 from [MoS 4 ] 2– .…”

“…Thermal annealing was found to substantially improve the crystallinity of the film as evidenced by Raman Spectroscopy. [ 7,8 ] It also removed excess sulfur from the film.…”

“…We have recently demonstrated that electrodeposition is a potentially viable method for solving this challenge. [ 7,8 ] Electrodeposition offers important advantages in 2D material production over other methods such as chemical vapor deposition (CVD), [ 9,10 ] sputtering, [ 11 ] or atomic layer deposition (ALD). [ 12 ] Electrodeposition is not a line‐of‐sight deposition method as material growth occurs at electrical contacts and is controlled by electrical potential or current.…”

“…[ 14–17 ] In addition, electrodeposition is usually performed at room temperature, avoiding harsh environments such as plasma or extremely high temperatures, which can damage pre‐existing materials on the substrate, such as graphene electrodes. [ 7 ]…”