Control of the Strain in Chemical Vapor Deposition-Grown Graphene over Copper via H2 Flow

Controlling strain offers the possibility to tune the electronic properties of graphene. In the present work, we demonstrate that it is possible to tune the strain of graphene by varying the hydrogen flow in the chemical vapor deposition growth of graphene over copper foil. On the basis of experimental results, we propose a mechanism where the high bombardment of hydrogen results in the ablation of graphene from the rippled surface of the copper foil. This results in the disappearance of the compressive stress that is present in slower hydrogen flows. The evaluation of the strain is done by analyzing the 2D peak shift by Raman spectroscopy, and the ripple density, by scanning electron microscopy.