Metal‐Free Growth of Nanographene on Silicon Oxides for Transparent Conducting Applications

Abstract

Conventional methods to prepare large‐area graphene for transparent conducting electrodes involve the wet etching of the metal catalyst and the transfer of the graphene film, which can degrade the film through the creation of wrinkles, cracks, or tears. The resulting films may also be obscured by residual metal impurities and polymer contaminants. Here, it is shown that direct growth of large‐area flat nanographene films on silica can be achieved at low temperature (400 °C) by chemical vapor deposition without the use of metal catalysts. Raman spectroscopy and TEM confirm the formation of a hexagonal atomic network of sp2‐bonded carbon with a domain size of about 3–5 nm. Further spectroscopic analysis reveals the formation of SiC between the nanographene and SiO2, indicating that SiC acts as a catalyst. The optical transmittance of the graphene films is comparable with transferred CVD graphene grown on Cu foils. Despite the fact that the electrical conductivity is an order of magnitude lower than CVD graphene grown on metals, the sheet resistance remains 1–2 orders of magnitude better than well‐reduced graphene oxides.

Evolution of Structural and Electrical Properties of Carbon Films from Amorphous Carbon to Nanocrystalline Graphene on Quartz Glass by HFCVD

“…The value of I 2D 2 / I 2D 1 indicates multilayer graphene features. Besides, the FWHM 2D 1 of our films is about 60–80 cm –1 , which agrees with the results of nanocrystalline graphene films in the literature. , The good uniformity of nanocrystalline graphene films is confirmed by the Raman mapping data of I D / I G and I 2D / I G , which is presented in Figure S2. The larger I D / I G and FWHM 2D and the smaller I 2D / I G of graphene films prepared by HFCVD compared with high-quality graphene films reported are probably originated from the grain boundary defects and therefore can be attributed to two aspects.…”

Fabrication and Characterisation of Resistive Nanocrystalline Graphite

“…Hence, the sheet resistance (Rsh=ρ/t) is found to be 39 kΩ/sq. The sheet resistance values are comparable to the 2 k -80 kΩ reported in several work using CVD technique [16][17][18][19].…”

van der Waals Epitaxial Growth of Graphene on Sapphire by Chemical Vapor Deposition without a Metal Catalyst

“…In many cases, the carrier mobility data were not presented in the metal-free growth of graphene on insulating or dielectric substrates. The best Hall mobility of ∼2000 cm 2 /V·s with ∼7 × 10 12 cm –2 sheet carrier density in this study is higher than that of most other metal-free growths − ,− and comparable to the previous result of high-temperature CVD on sapphire (as grown sample before vacuum annealing treatment).…”