Direct Synthesis of van der Waals Solids

Abstract

The stacking of two-dimensional layered materials, such as semiconducting transition metal dichalcogenides (TMDs), insulating hexagonal boron nitride (hBN), and semimetallic graphene, has been theorized to produce tunable electronic and optoelectronic properties. Here we demonstrate the direct growth of MoS2, WSe2, and hBN on epitaxial graphene to form large-area van der Waals heterostructures. We reveal that the properties of the underlying graphene dictate properties of the heterostructures, where strain, wrinkling, and defects on the surface of graphene act as nucleation centers for lateral growth of the overlayer. Additionally, we show that the direct synthesis of TMDs on epitaxial graphene exhibits atomically sharp interfaces. Finally, we demonstrate that direct growth of MoS2 on epitaxial graphene can lead to a 10(3) improvement in photoresponse compared to MoS2 alone.

Electrolytic phototransistor based on graphene-MoS2 van der Waals p-n heterojunction with tunable photoresponse

“…The recent studies of growth concerning various 2D materials [14][15][16][17] has opened the possibility to design van der Waals (vdW) heterostructures using graphene as an underlayer, which provides more opportunities for achieving desired electronic or optoelectronic properties 3,[18][19][20][21][22][23][24] . In fact even if graphene has exceptionally high mobility at room temperature, for optoelectronics 9 the overall low absorption of a single carbon layer (≈ 2%) and the absence of band gap implies that graphene needs to be combined with some semiconductor compounds.…”

Layered Two-Dimensional Heterostructures and Their Tunneling Characteristics

“…The SiC is subsequently annealed in a pure Ar environment at 200 Torr and 1620 • C for 10 minutes. [52] During the entire process the SiC substrates are inside a graphite crucible, which reduces the sublimation rate of Si at high temperatures and hence improves the uniformity of graphene morphology.…”

“…For vertical heterostructures in particular, layer-by-layer growth allows direct control of the constituent materials in a serial fashion, and typically these techniques can be scaled to large lateral dimensions in a way that is not possible with exfoliated materials. Hence, a great deal of e ort has gone into adapting epitaxial growth methods to form atomic layers of MoS 2 , MoSe 2 , WSe 2 , h-BN, and others on graphene, [50,52,68,75,76] as well as graphene on h-BN. [77,78] Graphene itself has been formed in large-area lms using CVD on metal foils with varying degrees of quality.…”

Green Intelligent Nanomaterials by Design (Using Nanoparticulate/2D-Materials Building Blocks) Current Developments and Future Trends

“…For instance, layer-after-layer deposition of two different nanomaterials in a vertical heterostructure is an example of type I heterointerface already demonstrated in TMDCs, h-BN, or topological insulators on graphene or in situ epitaxial growth of vertical CuS/TiS 2 type heterostructures [260,[333][334][335][336]. Similarly, type II heterointerface was reported in case of combinations of WSe 2 /WS 2 , MoSe 2 /MoS 2 , and MoSe 2 /WSe 2 , wherein the growth of one type of nanosheet was made to start from the edge of the other forming an in-plane 2D heterojunction [268,[337][338][339].…”