Direct growth of large-area graphene and boron nitride heterostructures by a co-segregation method

Abstract

Graphene/hexagonal boron nitride (h-BN) vertical heterostructures have recently revealed unusual physical properties and new phenomena, such as commensurate-incommensurate transition and fractional quantum hall states featured with Hofstadter's butterfly. Graphenebased devices on h-BN substrate also exhibit high performance owing to the atomically flat surface of h-BN and its lack of charged impurities. To have a clean interface between the graphene and h-BN for better device performance, direct growth of large-area graphene/ h-BN heterostructures is of great importance. Here we report the direct growth of large-area graphene/h-BN vertical heterostructures by a co-segregation method. By one-step annealing sandwiched growth substrates (Ni(C)/(B, N)-source/Ni) in vacuum, wafer-scale graphene/ h-BN films can be directly formed on the metal surface. The as-grown vertically stacked graphene/h-BN structures are demonstrated by various morphology and spectroscopic characterizations. This co-segregation approach opens up a new pathway for large-batch production of graphene/h-BN heterostructures and would also be extended to the synthesis of other van der Waals heterostructures.

Carbon-decorated iron oxide hollow granules formed using a silk fibrous template: lithium-oxygen battery and wastewater treatment applications

“…The TGA curve of the C/Fe 3 O 4 HGs showed a shoulder, followed by 1.7% weight gain around 300°C. This behavior has also been observed for commercial 28 Generally, defects in the carbon structure can be distinguished from the ratio between the carbons Although the rice-grain-shaped hollow structure was almost the same for both the C/Fe 3 O 4 HGs and the Fe 2 O 3 HGs after the annealing process, the porous architecture of the two samples, including the crystallite size and porosity, changed significantly (Supplementary Figure S8). Based on the aforementioned analysis, it can be expected that survival of the carbon matrix or the silk fibrous template would result in a highly porous shell structure after annealing.…”

A two-dimensional spin field-effect switch

“…With the above improvements to the fabrication process, and considering the robust performance of MoS 2 transistors at room temperature2324, a room-temperature 2D spin field-effect switch is envisioned. The recent advances in chemical growth of high quality 2D layered materials2138 and their heterostructure multilayers394041, as well as in homostructural42, and heterostructural36 tunnel barriers for spin injection, may well lead to large-scale integration of the current device architecture. Aside from the potential technological applications, the spin absorption effect in our experiments provides a solution to electrically inject spins into 2D semiconducting TMDs, which has so far been elusive due to the conductivity mismatch problem434445.…”

Chemical vapor deposition growth of large-scale hexagonal boron nitride with controllable orientation

“…Specifically, hexagonal boron nitride (h-BN), a structural analogue of graphene, has lattice parameters similar to graphene (there is only a 1.8% lattice mismatch), but has a larger band gap (~5.9 eV). The combination of graphene and h-BN, including both in-plane h-BN-graphene hybrids and stacked graphene/ h-BN (G/h-BN) structures, has been shown to have very intriguing physical properties such as Hofstadter's butterfly [4][5][6][7][8][9][10]. In particular, G/h-BN vertical stacks exhibit excellent field effect transistor performance with extremely high carrier mobility [11].…”