Magnetic Dipole Resonance and Coupling Effects Directly Enhance the Raman Signals of As-Grown Graphene on Copper Foil by over One Hundredfold
Journal
Chemistry of Materials
Journal Volume
30
Journal Issue
5
Pages
1472-1483
Date Issued
2018
Author(s)
Abstract
Large-area graphene is commonly prepared through chemical vapor deposition (CVD); in situ and nondestructive methods for its characterization are desirable. In this paper, we demonstrate a practical method—exploiting magnetic dipole resonance and coupling effects—with which the Raman signals of graphene on copper (Cu) foil can be directly, faithfully, and greatly enhanced. The magnetic dipole resonance of a silicon nanoparticle (SiNP) can effectively couple its electromagnetic field with the Cu foil to induce an enormous electric field located solely at the position of the SiNP on the graphene. The coupled electromagnetic field can lead to hot spots of high electric field intensity (E2/E02 = 123.2) within the graphene. Even when we positioned only a few SiNPs upon the graphene/Cu foil, we obtained a Raman signal enhancement (ca. 206 times) much greater than that of graphene transferred onto a 300 nm oxide film (ca. 12 times). From a series of experiments comparing the Raman signals of graphene before and after removing the SiNPs on the graphene/Cu foil, we found that the coated SiNPs had almost no effect on the quality of the as-grown graphene. Furthermore, we have used the SiNP-enhanced Raman signals to distinguish the local quality of as-grown graphene at different areas and, therefore, the quality of the underlying Cu foil. Thus, this approach based on magnetic dipole resonance and coupling appears to be very useful for in situ and nondestructive characterization of as-grown graphene on Cu foil, without the need for transfer processes or harmful processing conditions.
Publisher
American Chemical Society
Type
journal article