Method and system for coating a metal workpiece with graphene
A method for coating a metal workpiece with graphene includes exposing the metal workpiece to a carbon-containing precursor gas and a hydrogen gas in a processing chamber in a first phase, and to the carbon-containing precursor gas, the hydrogen gas and a first carrier gas in the processing chamber in a second phase after the first phase. A first flow rate of the carbon-containing precursor gas into the processing chamber is higher than a second flow rate of the carbon-containing precursor gas into the processing chamber, and a first flow rate of the hydrogen gas into the processing chamber is higher than a second flow rate of the hydrogen gas into the processing chamber. A first total gas pressure in the processing chamber in the first phase is lower than a second total gas pressure in the processing chamber in the second phase.
1. A method for coating a metal workpiece with graphene by means of chemical vapor deposition, comprising:
exposing the metal workpiece to a carbon-containing precursor gas and a hydrogen gas in a processing chamber in a first phase; and
exposing the metal workpiece to the carbon-containing precursor gas, the hydrogen gas and a first carrier gas in the processing chamber in a second phase after the first phase;
wherein a first flow rate of the carbon-containing precursor gas into the processing chamber in the first phase is higher than a second flow rate of the carbon-containing precursor gas into the processing chamber in the second phase;
wherein a first flow rate of the hydrogen gas into the processing chamber in the first phase is higher than a second flow rate of the hydrogen gas into the processing chamber in the second phase; and
wherein a first total gas pressure in the processing chamber in the first phase is lower than a second total gas pressure in the processing chamber in the second phase.
2. The method according to claim 1 , further comprising evacuating the processing chamber in the first phase at a first exhausting power and evacuating the processing chamber in the second phase at a second exhausting power, wherein the second exhausting power is smaller than the first exhausting power.
3. The method according to claim 1 , further comprising heating the processing chamber and/or the metal workpiece in the first phase and/or in the second phase.
4. The method according to claim 3 , wherein heating the processing chamber and/or the metal workpiece in the first phase and/or in the second phase is carried out at a temperature of no smaller than 1000° C.
5. The method according to claim 1 , further comprising, prior to the first phase, cleaning a surface of the metal workpiece.
6. The method according to claim 5 , further comprising, prior to the first phase, annealing the metal workpiece.
7. The method according to claim 6 , wherein the cleaning precedes the annealing.
8. The method according to claim 1 , wherein exposing the metal workpiece to the carbon-containing precursor gas and the hydrogen gas in the processing chamber in the first phase and/or the second phase comprises directing the carbon-containing precursor gas and/or the hydrogen gas towards the metal workpiece by means of a guiding plate disposed in the processing chamber.
9. The method according to claim 8 , wherein directing the carbon-containing precursor gas and/or the hydrogen gas towards the metal workpiece comprises focusing the carbon-containing precursor gas and/or the hydrogen gas towards the metal workpiece by means of the guiding plate disposed in the processing chamber.
10. The method according to claim 3 , wherein heating the processing chamber and/or the metal workpiece in the first phase and/or in the second phase is carried out at a temperature of no smaller than 900° C.
11. The method according to claim 1 , further comprising, prior to the first phase, cleaning a surface of the metal workpiece by exposing the surface to a gas flow comprising hydrogen gas and a second carrier gas.
12. The method according to claim 1 , wherein the depositing of the single carbon atoms is controlled and/or a formation of multiple carbon layers on the metal workpiece is prevented in the first phase based on the lower total gas pressure, the higher first flow rate of the carbon-containing precursor gas, and the higher first flow rate of the hydrogen gas.
13. The method according to claim 12 , wherein the growing of the hexagonal monolayer graphene structure is epitaxial and faster than in the first phase in the second phase based on the higher second total gas pressure, the lower second flow rate of the carbon-containing precursor gas, the lower second flow rate of the hydrogen gas, and the flow rate of the first carrier gas.
14. The method according to claim 13 , wherein a flow rate of the first carrier gas raises the second total gas pressure in the processing chamber in the second phase.