Graphene/3C-SiC Hybrid Nanolaminate

Abstract

In this work, we demonstrate a one-step approach to create graphene/3C-SiC nanolaminate structure using microwave plasma chemical vapor deposition technique. Layer-by-layer arrangement of thin 3C-SiC layers and graphene sheets is obtained with the thicknesses of the individual 3C-SiC layers and graphene sheets being 5-10 nm and 2-5 nm, respectively. An intimate contact between 3C-SiC and the graphene sheets is achieved and the nanolaminate film shows a high room temperature conductivity of 96.1 S/cm. A dedicated structural analysis of the nanolaminates by means of high-resolution transmission electron microscopy (HRTEM) reveals that the growth of the nanolaminates follows an iterative process: preferential graphene nucleation around the planar defects at the central region of the SiC layer, leading to the "splitting" of the SiC layer; and the thickening of the SiC layer after being "split". A growth mechanism based on both kinetics and thermodynamics is proposed. Following the proposed mechanism, it is possible to control the layer thickness of the graphene/3C-SiC hybrid nanolaminate by manipulating the carbon concentration in the gas phase, which is further experimentally verified. The high electrical conductivity, large surface area porous structure, feasible integration on different substrates (metal, Mo; semiconductor, Si and 2H-SiC; insulator, diamond) of the graphene/3C-SiC hybrid nanolaminate as well as other unprecedented advantages of the nanolaminate structure make it very promising for applications in mechanical, energy, and sensor-related areas.

3D 3C‐SiC/Graphene Hybrid Nanolaminate Films for High‐Performance Supercapacitors

“…For SiC/G‐HNFs B and C, the pore depth is reduced to the range of a few hundred of nanometers. This is probably due to a higher density of nanolaminates and stronger curvature of the single nanolaminates, as stated in the growth mechanism . Note here that when the depth of the pores becomes smaller (Figure c,f), the penetration of the electrolyte into the bottom of these vertically aligned structures might become more difficult, due to high hydrophobic characteristics of these SiC/G‐HNFs.…”

“…A higher CH 4 concentration leads to a faster growth rate of those vertically aligned layers and a different layer thickness of both 3C‐SiC and graphene layers inside the nanolaminate structure. For example, the thickness of 3C‐SiC layers in the SiC/G‐HNF A is about 23 nm, while in the SiC/G‐HNF C it is only about 4 nm . In other words, a higher CH 4 concentration during MWCVD growth processes leads to a higher amount of graphene in the nanolaminate structure …”

“…Three SiC/G‐HNFs consist of alternatively and vertically aligned of 3C‐SiC and graphene layers, confirming the growth of a layer‐by‐layer growth mode. The growth mechanism of those SiC/G‐HNFs can be briefly explained as following . A dense epitaxial layer of 3C‐SiC forms first on the substrate.…”

“…The graphene sheets with an interplanar spacing of 0.34 nm are directly adjacent to the 3C‐SiC crystallite with its basal plane parallel to the (111) plane of 3C‐SiC, showing an intimate contact between graphene and 3C‐SiC. The 3C‐SiC layers are thus coated from both sides with graphene layers . In other words, graphene edges are highly exposed, instead of basal planes of graphene.…”

“…With an aim to construct high‐performance SCs, 3D nanostructures from graphene and 3C‐SiC, so‐named 3C‐SiC/graphene hybrid nanolaminate films (SiC/G‐HNFs), are designed and synthesized by means of a microwave plasma‐assisted chemical vapor deposition (MWCVD) technique. Since these films consist of an alternating nanostructure of vertically aligned 3C‐SiC/graphene/3C‐SiC structure where the thicknesses of these individual layers are in the range of several nanometers, they are expected to feature high surface areas, high conductivity, and long‐term stability. They are also free of binders and no current collectors are needed for the construction of SCSs.…”