Direct growth of single- and few-layer MoS$_{\mathrm{2}}$ on h-BN by CVD method*

As a promising candidate for the next-generation electronics, large-scale single- and few-layer molybdenum disulfide (MoS$_{\mathrm{2}})$ grown by CVD method is an important advancement towards technological implementation of this material. However, the choice of substrate can significantly affect the performance of MoS$_{\mathrm{2}}$ based devices. An attractive insulating substrate or mate for MoS$_{\mathrm{2}}$ (and related materials such as graphene) is hexagonal boron nitride (h-BN). Stacked heterostructures of MoS$_{\mathrm{2}}$ 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 MoS$_{\mathrm{2}}$ on h-BN by chemical vapor deposition (CVD) method. The growth mechanisms for single- and few-layer samples are found to be distinct, and for single-layer samples low relative rotation angles (\textless 5\textdegree ) between the MoS$_{\mathrm{2}}$ and h-BN lattices prevail. In addition, MoS$_{\mathrm{2}}$ directly grown on h-BN maintains its intrinsic 1.89 eV bandgap. Our CVD synthesis method presents a viable path towards high-quality MoS$_{\mathrm{2}}$ based field effect transistors in a controllable and scalable fashion.