High-quality multilayer graphene on an insulator formed by diffusion controlled Ni-induced layer exchange

• Published in: Applied physics letters Vol. 111; no. 24
• Main Authors: Murata, H., Saitoh, N., Yoshizawa, N., Suemasu, T., Toko, K.
• Format: Journal Article
• Language: English
• Published: 11-12-2017
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5010982

The Ni-induced layer-exchange growth of amorphous carbon is a unique method used to fabricate uniform multilayer graphene (MLG) directly on an insulator. To improve the crystal quality of MLG, we prepare AlO
x
or SiO2 interlayers between amorphous C and Ni layers, which control the extent of diffusion of C atoms into the Ni layer. The growth morphology and Raman spectra observed from MLG formed by layer exchange strongly depend on the material type and thickness of the interlayers; a 1-nm-thick AlO
x
interlayer is found to be ideal for use in experiments. Transmission electron microscopy and electron energy-loss spectra reveal that the crystal quality of the resulting MLG is much higher than that of a sample without an interlayer. The grain size reaches a few μm, leading to an electrical conductivity of 1290 S/cm. The grain size and the electrical conductivity are the highest among MLG synthesized using a solid-phase reaction including metal-induced crystallization. The direct synthesis of uniform, high-quality MLG on arbitrary substrates will pave the way for advanced electronic devices integrated with carbon materials.