One-pot synthesis of vertical graphene/h-BN heterostructure utilizing the passivation role of hydrogen

•The effect of hydrogen on nucleation, growth and etching of h-BN is demonstrated.•The etching of h-BN is terminated under high hydrogen flow.•Hydrogen plays a dual role of activator and passivation during h-BN growth.•Vertical graphene/h-BN heterostructure was achieved in one-pot by conventional CVD. Graphene/hexagonal boron nitride (h-BN) heterostructures have attracted a lot of research interests due to their superior electronic properties in field effect transistor devices and the novel physical properties such as fractional fractal quantum hall effect and massive Dirac fermions. Chemical vapor deposition (CVD) is the most common method to synthesize h-BN and graphene, however, the directly growth of graphene/h-BN heterostructures remains challenging. Here we report the crucial impact of hydrogen on the nucleation density, growth rate and etching rate in the h-BN CVD growth. It is found that the nucleation density increases monotonically, whereas the growth rate and etching rate first increases and then decreases with the increasing hydrogen partial pressure. Benefitting from the understanding of the crucial role of hydrogen, we successfully grow the graphene/h-BN vertical heterostructures by low pressure CVD in one-pot through the modulation of hydrogen partial pressure. The field effect transistor (FET) fabricated using graphene/h-BN heterostructure shows better performance with higher carrier mobility and lower level of doping than the one without h-BN. Our direct synthesis approach paves a new pathway for large-scale production of graphene/h-BN heterostructures and could be applied for the synthesis of other van der Waals heterostructures.