Improved graphene synthesis for potential large single-crystal domain through mobile hotwire CVD

Abstract

As a result of emerging interest of the graphene, several graphene synthesis methods have been developed. Chemical vapor deposition is a proper synthesis method to grow the large-scale and high-quality graphene. Conventional growth mechanism of the chemical vapor deposition is formation of nucleation sites and grain growth. Grain boundaries in the polycrystalline graphene synthesized by chemical vapor deposition significantly degrade the graphene quality. A novel method to control the nucleation sites and sequential growh of chemical vapor deposition graphene has been investigated. By means of a mobile metallic hotwire as an independent heat source, we could investigate a detailed growth mechanism for graphene formation process. Using our mobile hotwire chemical vapor deposition system, we could find the global graphene domain embedding rotated nanoclustered graphene with high-angle tilt boundary analyzed by transmission electron microscope. Especially, we observed a recrystallization-like behavior during the graphene growth at various temperature and hotwire scan speed conditions. Properties of the graphene were confirmed by Raman spectroscopy and sheet resistance measurement. The graphene synthesized at optimum condition, ID/IG ratio was ~ 0.05 and sheet resistance was ~ 390 Ω/□. Back-gate field-effect transistor was fabricated to evaluate the electronical properties of the wire-scanned graphene. The highes hole mobility was ~930 cm2 /Vos. We believe our report provides a significant contribution to enhance the properties of CVD graphene by controlling the nucleation sites and the sequential growth.