Direct synthesis of large area graphene on insulating substrate by gallium vapor-assisted chemical vapor deposition

Abstract

A single layer of graphene with dimensions of 20 mm × 20 mm was grown directly on an insulating substrate by chemical vapor deposition using Ga vapor catalysts. The graphene layer showed highly homogeneous crystal quality over a large area on the insulating substrate. The crystal quality of the graphene was measured by Raman spectroscopy and was found to improve with increasing Ga vapor density on the reaction area. High-resolution transmission electron microscopy observations showed that the synthesized graphene had a perfect atomic-scale crystal structure within its grains, which ranged in size from 50 nm to 200 nm.

Direct synthesis of multilayer graphene on an insulator by Ni-induced layer exchange growth of amorphous carbon

“…This is probably because the Ni layer deformed during annealing and resulted in a non-uniform layer exchange. The intensity ratio of the G to D peaks, corresponding to the crystal quality of MLG, 10,14 is approximately 2.3 in the whole range of growth temperature ( Fig. 2(c)).…”

“…10,23 The G and D peaks are quite broad, indicating that the C layer is almost amorphous even after 1000 C annealing. This means that the Ni catalyst has lowered the crystallization temperature of a-C by more than 400 C. The difference of the crystallization temperatures of a-C between with and without Ni is large compared with the case of the MILE for Si and Ge.…”

“…38 This behavior is consistent with the other studies on the metal-induced synthesis of graphene: {002} oriented graphene precipitate from metals. [7][8][9][10][11][12][13] The selected-area electron diffraction (SAED) pattern in Fig. 3(c) shows slightly arced spots besides the spots corresponding to Ni.…”

“…6 Because the transfer possibly damages graphene, a transfer-free process is essential for practical device applications. Low-temperature synthesis of graphene on insulators has been achieved using chemical-vapor deposition [7][8][9][10][11] and plasma-assisted vapor deposition 12,13 with metal catalysts (e.g., Cu, Ni, Fe, and Co). These techniques are useful for directly forming a few-layer graphene on insulators, but they are not suitable for forming thick MLG, which is necessary for carrying a large amount of current or heat.…”

Synthesis of Large-Area Few-Layer Graphene by Open-Flame Deposition

“…Many research groups have investigated the synthesis of graphene at extremely high temperature and low reaction pressure (Chen et al 2015;Polat et al 2015). Others also reported on using vapor metal as the catalyst for graphene deposition (Murakami et al 2015).…”