Graphene layer formation at low substrate temperature on a metal and carbon based substrate
A system and method for forming graphene layers on a substrate. The system and methods include direct growth of graphene on diamond and low temperature growth of graphene using a solid carbon source.
1. A method of forming graphene on a substrate for manufacturing an electronic device, comprising,
providing a diamond substrate;
forming a transition metal layer on the diamond substrate;
dissolving at least a portion of the transition metal layer into the diamond substrate by an annealing step;
cooling the diamond substrate to room temperature;
thereby forming a graphene layer on the diamond substrate.
2. The method as defined in claim 1 wherein the diamond substrate is selected from the group of (a) single crystal diamond and (b) at least one of: UNCD/NCD/MCD (microcrystalline diamond) thin film diamond deposited on a Si substrate.
3. The method as defined in claim 1 wherein the transition metal layer comprises Ni.
4. The method as defined in claim 1 wherein the annealing step includes placing the diamond substrate in a vacuum furnace with a H 2 /Ar gas mixture.
5. The method as defined in claim 1 wherein an annealing temperature is about 800-1000° C. and the cooling step is performed at a rate of about 30° C./minute.
6. The method as defined in claim 1 further including the step of providing a carbon precursor gas to accelerate graphene growth.
7. The method as defined in claim 6 wherein the carbon precursor gas comprises an Ar/ethanol or Ar/ethylene or H 2 CH 4 gas mixture and the annealing temperature is about 1000° C., thereby growing large grain sizes for the graphene layer.
8. The method as defined in claim 1 wherein a thickness of the transition metal layer is established such that upon completing the dissolving step the transition metal from the transition metal layer has no trace amount in sub-surface regions of the diamond substrate.
9. The method of claim 1 , further comprising graphitizing at least a portion of the diamond substrate to form a graphite layer.
10. The method of claim 1 wherein forming the graphene layer further comprises converting at least portion of the graphite layer into graphene.
11. A method of forming graphene on a substrate for manufacturing an electronic device, comprising:
providing a substrate;
disposing a transition metal based material on the substrate;
providing a carbon precursor source to generate a carbon precursor;
applying a polymer onto the transition metal;
heating the substrate, the polymer, and the transition metal based material and the carbon precursor from the carbon precursor source; and
depositing graphene directly onto the transition metal based material.
12. The method as defined in claim 11 wherein the substrate comprises a Si based material and the transition metal based material comprises Ni.
13. The method as defined in claim 12 wherein the transition metal material comprises a transition metal alloy.
14. The method as defined in claim 11 further including the steps of heating the substrate and the polymer disposed on the transition metal, thereby decomposing the polymer and forming a carbon rich layer on the transition metal, and cooling the substrate and a carbon rich layer on the transition metal, thereby forming a graphene layer from the carbon rich layer.
15. The method as defined in claim 11 further including an SiO 2 layer disposed between the substrate and the graphene.
16. The method as defined in claim 11 wherein the step of heating is at about 400° -500° C.
17. The method as defined in claim 11 wherein the polymer comprises a mixture of aliphatic hydrocarbon and alkene hydrocarbon having a melting point less than about 80° C.
18. The method as defined in claim 17 wherein the polymer consists of n-octacosane and n-tetracosane.