Transfer-free growth of polymer-derived graphene through mobile hotwire CVD

Abstract

With its outstanding electrical, mechanical, and chemical properties, graphene has attracted great interest as a promising material. But realization of various applications requires fabricating large scale, uniform, and high quality graphene. Thus, several methods for fabricating large graphene have been developed. Chemical vapor deposition (CVD) has been demonstrated as an attractive method to synthesize large-area graphene for practical applications. However, transfer process induces many defects on the fabricated graphene sheet, causing severe damage on the quality. In this research, we succeeded in transfer-free growth of polymer-derived graphene on a dielectric substrate through mobile hot-wire CVD. Before mobile hotwire CVD was developed, when graphene was synthesized from the polymer through the conventional overall heated tube type CVD, most polymers were removed from the nickel surface during pyrolysis because they are thermally degradable. To solve this problem, we used mobile hot-wire CVD developed in our laboratory. It is divided into two heating sources consisting of substrate and wire. The substrate reduces evaporated polymer and increases the amount of carbon dissolved in the Ni layer because of the role of the bottom heater unlike the conventional CVD. The wire can control the cooling rate and growth time that can improve the coverage and uniformity. Also, we realized that high heat resistance polymer increases the amount of carbon dissolved in the Ni layer and improve the coverage of graphene. We succeeded in the transfer-free growth graphene that contains no defects, such as the wrinkle, PMMA residue, and nickel etchant.