Graphene-based multi-modal sensors

1. A method for fabricating a composite film structure, the method comprising:

determining a desired morphology for a metallic layer of the composite film structure;

selecting a first metal substrate based on the determining;

transferring a graphene layer onto the first metal substrate;

depositing the metallic layer on the graphene layer to achieve the desired morphology, wherein a surface energy difference between the first metal substrate and the deposited metallic layer results in the desired morphology of the metallic layer, the desired morphology comprises a layer of nanoislands having controlled and uniform inter-nanoisland separation and a distance between edges of nanoislands in the metallic layer is on the order of about 2 Å to a few nanometers, and removing the first metal substrate from the graphene and the deposited metallic layer to form the composite film structure.

2. The method of claim 1 , wherein depositing the metallic layer comprises deposition of evaporated flux of metallic atoms.

3. The method of claim 2 , wherein the evaporated flux of metallic atoms self-assemble to yield the desired morphology.

4. The method of claim 2 , where in the evaporated flux of metallic atoms are produced by electron beam evaporation, thermal evaporation, or sputtering.

5. The method of claim 1 , wherein transferring the graphene layer onto the first metal substrate comprises exfoliating the graphene grown on a second metal substrate and placing the graphene layer onto the first metal substrate; and wherein the graphene comprises a single layer of graphene.

6. The method of claim 5 , wherein the graphene is grown on the second metal substrate using chemical vapor deposition.

7. The method of claim 1 , wherein the first metal substrate comprises a transition metal.

8. The method of claim 7 , wherein the transition metal comprises gold, silver, or nickel.

9. A method of forming a substrate for surface-enhanced Raman scattering, the method comprising:

depositing a graphene layer on a first metal substrate;

depositing a plurality of metallic nanoislands on the graphene layer, wherein a surface energy difference between the first metal substrate and the deposited metallic nanoislands results in the desired morphology of the metallic nanoislands, the desired morphology comprises a layer of nanoislands having controlled and uniform inter-nanoisland separation and a distance between edges of nanoislands in the metallic layer is on the order of about 2 Å to a few nanometers; removing the first metal substrate from the graphene and the deposited plurality of metallic nanoislands to form the substrate for surface-enhanced Raman scattering.

10. A method of performing surface-enhanced Raman scattering of an analyte, the method comprising:

forming a substrate for surface-enhanced Raman scattering according to the method of claim 9 ;

transferring the substrate on an optical fiber;

coating the analyte on the substrate; and

recording surface-enhanced Raman scattering signals from the analyte.

11. The method of claim 10 , wherein the plurality of metallic nanoislands comprises a plasmonically active metal.

12. The method of claim 11 , wherein the plasmatically active metal comprises copper, silver, palladium, gold, or platinum nanoislands.

13. A method of performing surface-enhanced Raman scattering of an analyte, the method comprising:

forming a substrate for surface-enhanced Raman scattering according to the method of claim 9 ;

transferring the substrate on an optical fiber;

placing the substrate into the analyte; and

recording surface-enhanced Raman scattering signals from the analyte.