Low vacuum annealing of polymer at low temperatures towards direct and scalable growth of graphene

Abstract

A transfer-free method is demonstrated for the synthesis of graphene flakes directly on insulating substrate (SiO2/Si) by carbon decomposition and diffusion through a layer of nickel. The 100 nm nickel catalyst was deposited on the top of SiO2 (300 nm)/Si substrate. The sandwich structure was prepared wherein spin-coated polymer was used as a carbon source for the graphene formation. The carbon molecules decomposed and diffused into the nickel layer during annealing of sandwich structures in low vacuum (∼5 × 10−1 Pa) at 600–750 °C for 10 min. When cooled to room temperature (25 °C), graphene is formed at the interface between Ni and SiO2/Si, the nickel film was removed by chemical etching. The observed graphene on SiO2/Si substrates is confirmed by optical microscopy, Raman spectroscopy and atomic force microscopy. The Raman spectroscopy mapping over a 55 × 55 μm2 area confirmed the good quality of graphene flakes obtained. © 2018 Elsevier Ltd