Hexagonal boron nitride (h-BN) has recently emerged as an excellent substrate for graphene nanodevices, owing to its atomically flat surface and its potential to engineer graphene's electronic structure. Thus far, graphene/h-BN heterostructures have been obtained only through a transfer process, which introduces structural uncertainties due to the random stacking between graphene and h-BN substrate. Here we report the epitaxial growth of single-domain graphene on h-BN by a plasma-assisted deposition method. Large-area graphene single crystals were successfully grown for the first time on h-BN with a fixed stacking orientation. A two-dimensional (2D) superlattice of trigonal moiré pattern was observed on graphene by atomic force microscopy. Extra sets of Dirac points are produced as a result of the trigonal superlattice potential and the quantum Hall effect is observed with the 2D-superlattice-related feature developed in the fan diagram of longitudinal and Hall resistance, and the Dirac fermion physics near the original Dirac point is unperturbed. The macroscopic epitaxial graphene is in principle limited only by the size of the h-BN substrate and our synthesis method is potentially applicable on other flat surfaces. Our growth approach could thus open new ways of graphene band engineering through epitaxy on different substrates.

Epitaxial growth of A-A and A-B stacking MoS2 on WS2 via a two-step chemical vapor deposition method is reported. These epitaxial heterostructures show an atomic clean interface and a strong interlayer coupling, as evidenced by systematic characterization. Low-frequency Raman breathing and shear modes are observed in commensurate stacking bilayers for the first time; these can serve as persuasive fingerprints for interfacial quality and stacking configurations.

We report a scalable growth of monolayer MoS2 films on SiO2 substrates by chemical vapor deposition. As-grown polycrystalline MoS2 films are continuous over the entire substrate surface with a tunable grain size from ∼20 nm up to ∼1 μm. An obvious blue-shift (up to 80 meV) of photoluminescence peaks was observed from a series samples with different grain sizes. Back-gated field effect transistors based on a polycrystalline MoS2 film with a typical grain size of ∼600 nm shows a field mobility of ∼7 cm(2)/(V s) and on/off ratio of ∼10(6), comparable to those achieved from exfoliated MoS2. Our work provides a route toward scaled-up synthesis of high-quality monolayer MoS2 for electronic and optoelectronic devices.