  Monolayer molybdenum disulphide (MoS2) is a promising two-dimensional
direct-bandgap semiconductor with potential applications in atomically thin and
flexible electronics. An attractive insulating substrate or mate for MoS2 (and
related materials such as graphene) is hexagonal boron nitride (h-BN). Stacked
heterostructures of MoS2 and h-BN have been produced by manual transfer
methods, but a more efficient and scalable assembly method is needed. Here we
demonstrate the direct growth of single- and few-layer MoS2 on h-BN by chemical
vapor deposition (CVD) method, which is scalable with suitably structured
substrates. The growth mechanisms for single-layer and few-layer samples are
found to be distinct, and for single-layer samples low relative rotation angles
(<5 degree) between the MoS2 and h-BN lattices prevail. Moreover, MoS2 directly
grown on h-BN maintains its intrinsic 1.89 eV bandgap. Our CVD synthesis method
presents an important advancement towards controllable and scalable MoS2 based
electronic devices.
