Large-Area Bernal-Stacked Bi-, Tri-, and Tetralayer Graphene

Abstract

Few-layer graphene, with Bernal stacking order, is of particular interest to the graphene community because of its unique tunable electronic structure. A synthetic method to produce such large area graphene films with precise thickness from 2 to 4 layers would be ideal for chemists and physicists to explore the promising electronic applications of these materials. Here, large-area uniform Bernal-stacked bi-, tri-, and tetralayer graphene films were successfully synthesized on a Cu surface in selective growth windows, with a finely tuned total pressure and CH(4)/H(2) gas ratio. On the basis of the analyses obtained, the growth mechanism is not an independent homoexpitaxial layer-by-layer growth, but most likely a simultaneous-seeding and self-limiting process.

Synchronous growth of AB-stacked bilayer graphene on Cu by simply controlling hydrogen pressure in CVD process

“…It should be pointed out that although the CH 4 flow may exert an influence on the resulting graphene [24][25][26], H 2 is a key factor to break the self-limit effect of graphene growth on Cu foil to enable the layer-by-layer epitaxy growth of bilayer graphene, which has been verified both theoretically and experimentally [5,12]. To shed some light on the role of H 2 pressure in breaking the self-limit effect of Cu, the graphene growth was repeated while the H 2 pressure was systematically varied in the range of 0.04-30 Torr.…”

Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

“…Oxygen is required for dehydrogenation of CH x so that atomic C can diffuse through the Cu foil for the 2 nd layer growth on the exterior surface. In other words, O opens up the kinetic pathway for BLG growth, a critical aspect that has been up to now completely overlooked [7][8][9][10][11][12][13][14][15][16][17][18][19] .…”

Equilibrium Chemical Vapor Deposition Growth of Bernal-Stacked Bilayer Graphene

“…15 AB-(Bernal-) stacked bilayer graphene (BLG) can develop a bandgap of up to 250 meV by applying a vertical electric field across the two layers, 17,18 but facile, high-yield synthesis of AB-stacked BLG remains a significant challenge. [19][20][21][22][23][24][25][26][27][28] The key point for BLG growth by CVD was to overcome the self-limiting nature of SLG on Cu, in which it is critical to maintain or recover the Cu surface for the effective catalysis. Hence, compared with the simple self-limiting process of SLG on Cu surface, the growth of BLG has 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 mainly been achieved by complicated pre-treatments or designed CVD process, such as spatially arranged Cu substrates, 20,23 percentage-engineered Cu-Ni alloy as catalytic substrates, 21,25 carefully adjusted nucleation pressure of methane, 22,24 a high hydrogen ratio to expose the covered Cu surface, 23 or nonisothermal growth environment with variable temperatures.…”