Enhancing CVD graphene's inter-grain connectivity by a graphite promoter

Abstract

Graphene's impact on future applications is intimately linked to advances in the synthesis of high quality materials. Chemical vapor deposition (CVD) shows great potential in this area but insufficient connectivity between single-crystalline domains deteriorates the achievable electrical and mechanical performance. We here demonstrate that the inter-grain connectivity can be significantly improved by adding a second material in the vicinity of the growth substrate. This promoter decreases the amount of structural defects that remain at the grain boundaries of conventionally grown graphene even after 6 hour growth. A two-step growth process was employed to selectively enhance the grain connectivity while maintaining an identical graphene grain morphology with and without a promoter. Graphite was found to yield the largest enhancement in the connectivity of graphene grains due to its high catalytic activity compared to other promoter materials. A novel cap-design ensured a large scale and uniform improvement of the inter-grain connectivity results which led to an enhancement of large scale carrier mobilities from 2700 cm² V⁻¹ s⁻¹ to 4000 cm² V⁻¹ s⁻¹ and highlights the potential of our approach to improving the connectivity of CVD-grown graphene.