Khaksaran M Hadi, Kaya Ismet I
Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Turkey.
SUNUM, Sabanci University Nanotechnology Research Center, 34956 Istanbul, Turkey.
ACS Omega. 2019 Jun 3;4(6):9629-9635. doi: 10.1021/acsomega.9b00681. eCollection 2019 Jun 30.
In chemical vapor deposition (CVD) growth of graphene, intrinsic carbon in copper has been shown to play a role, especially during the nucleation phase. Here, we report experimental results on depletion of carbon from the bulk of a Cu foil to its surface at different hydrogen pressures, which explain new aspects of the interplay between hydrogen and intrinsic carbon prior to growth. We observed that rising H pressure boosts carbon depletion to the surface, but at the same time, at elevated H pressures, the graphitic film formed on the Cu surface is etched away at a faster rate. This effect led us to practice annealing of copper under high hydrogen pressure as an approach to decrease the total content of carbon in the copper foil and consequently reducing the nucleation density of graphene flakes. These results enhance our understanding about the role of H in the CVD process and explain some of the inconsistencies among the earlier reports.
在化学气相沉积（CVD）法生长石墨烯的过程中，已证明铜中的固有碳发挥了作用，尤其是在成核阶段。在此，我们报告了在不同氢气压力下，铜箔体相中碳向其表面耗尽的实验结果，这些结果解释了生长前氢气与固有碳之间相互作用的新方面。我们观察到，氢气压力升高会促使碳向表面耗尽，但与此同时，在较高氢气压力下，铜表面形成的石墨薄膜被蚀刻的速度更快。这种效应促使我们采用在高氢气压力下对铜进行退火的方法，以降低铜箔中的总碳含量，从而降低石墨烯薄片的成核密度。这些结果加深了我们对氢气在CVD过程中作用的理解，并解释了早期报告中的一些不一致之处。
