凯发

Hexagonal　boron nitride (h-BN), as a dielectric substrate, can largely preserve the superior properties of graphene. Vertical or lateral graphene/hBN hetero-structures may bring in opportunities for novel electronic devices. Scalable synthesis of high quality single crystalline hBN, graphene and graphene/hBN are strongly desired, but remains to be extremely challenging. In this talk, I will present our systematic research on the direct CVD growth of graphene on mechanically exfoliated hBN flakes. With our newly discovered gaseous surface activator, silane can effectively work with C2H2, allowing for the synthesis of precisely aligned single crystalline graphene on hBN. The growth rate reaches 1 um/min, a 2-3 orders of magnitude increases compared to previous reports. Typical domain sizes are 10-20 microns, already in a range for practical device demonstration. We will present our results on the synthesis of single crystalline hBN domains over hundred micrometers in size, using an optimized Cu-Ni alloy as catalyst. Results on vertical and lateral graphene/hBN hetero-structures made on CVD hBN will be discussed. Most recent progresses on the fabrication of inch-sized graphene wafer from a controlled single nucleus and the synthesis of A-B stacked double layer graphene with large domain sizes will also be briefly presented.