Spatial Confinement Approach Using Ni to Modulate Local Carbon Supply for the Growth of Uniform Transfer-Free Graphene Monolayers

Direct growth of high-quality graphene on dielectric substrates without a sophisticated transfer process is one of the key challenges to effectively integrate graphene synthesis with the existing semiconductor manufacturing process. In this study, we take advantages offered by a customized reactor to realize the synthesis of uniform transfer-free graphene monolayers on SiO2/Si substrates via the metal-catalytic chemical vapor deposition method. The optimal reactor is designed to be a Ni-covered quartz slit with a confined reaction space (length × width × height = 85 × 13 × 0.55 mm3). The slit structure of this reactor offers a spatially confined environment for effectively suppressing Cu evaporation and modulating the growth kinetics of graphene. In addition, the Ni cover serves as a carbon absorbent for regulating the local concentration of carbon species within the slit reactor, which increases the monolayer content of the produced graphene. With the optimal synthesis protocol, transfer-free graphene with low defects and high monolayer content (>90%) was prepared directly on SiO2/Si substrates as continuous large-area films (1 × 1 cm2) or microscale patterns with sheet resistance and field-effect mobility of 334 Ω/sq and 962 cm2/(V s), respectively.