DEVELOPMENT OF A PROCESS FOR THE SYNTHESIS OF GRAPHENE BY PLASMA-ENHANCED VAPOR DEPOSITION WITH A DC SOURCE

Description

5 DEVELOPMENT OF A PROCESS FOR THE SYNTHESIS OF GRAPHENE BY PLASMA-ENHANCED VAPOR DEPOSITION WITH A DC SOURCE Field of invention

[001] The present invention falls within the field of mechanics / chemistry, specifically dealing with the development of a process for the synthesis of PECVD (Plasma Enhanced Chemical Vapor Deposition) graphene using a DC (Direct Current) source. Fundamentals of the invention

[002] Graphene is one of the allotropes of carbon, it has a hexagonal monolayer atomic structure and possesses properties that make it one of the most promising materials for the future, thus, studies on the production and synthesis of the material are key to research and future expansions in various markets today, from electronics to dentistry. With mechanical, thermal and electrical properties much higher than materials currently used, it can be applied in numerous areas, leading to recent investment in graphene and startups for its application and research (ALENCAR, 2016).

[003] Because it is an innovative and understudied material, graphene was chosen for research in order to later utilize methods involving plasma for its use. With the conclusion of the research and the success in producing and characterizing graphene samples, PECVD (Plasma Enhanced Chemical Vapor Deposition) was chosen as the next method for its synthesis, which, unlike the CVD (Chemical Vapor Deposition) method, lowers the temperature from 1000°C to 500°C.

[004] The present invention resulted from a study and adaptation project in nitriding chambers for the production of graphene using the PECVD (Plasma Enhanced Vapor Deposition) method and the introduction of this new material into the APL (Local Productive Arrangement), creating new possibilities for innovation in manufacturing. Petition 870240111270, dated 12 / 30 / 2024, page 7 / 17 / 5

[005] The chamber was developed for the production and improvement of parameters, in order to develop a cheaper synthesis method for wider future applications of the material. Brief description of the drawings

[006] Figure 1 shows the inside of the plasma chamber, with the gas shower installed. Figure 2 shows the exterior of the vacuum chamber. Figure 3 shows a 5x5 sample after cleaning with acetone, ready to be cut. Figure 4 shows the cleaning of copper samples in plasma. Figure 5 shows post-synthesis samples. Description of the invention

[007] First, a bibliographic survey was conducted on the materials, methods, and characterization of graphene by Raman spectroscopy, SEM (Scanning Electron Microscopy), and optical microscopy, as well as the production of PECVD graphene, equipment, production techniques, and characterization. The PECVD system consists of a vacuum chamber.

[008] The PECVD method consists of a CVD (Chemical Vapor Deposition) system with the addition of plasma to the system, thus lowering the temperature necessary to break down the source carbon molecule (CAMARGOS, 2017). In this invention, Hydrogen, Argon, and Methane were used for the reaction, Argon as an inert gas and copper as a substrate, in addition to increasing the temperature in order to reach the various parameters covered by the project. The type of plasma source used in the project was DC (Direct Current).

[009] The process is based on the physisorption of hydrogen, which, with the temperature of the plasma, decomposes and adheres to the copper plate, thus, adhesion of the Petition 870240111270, dated 12 / 30 / 2024, page 8 / 17 / 5 carbon atoms of methane in the substrate, forming single-layer hexagonal structures, graphene (WOEHRL, 2014).

[0010] The parameters were varied based on gas ratio and temperature, since temperature is a factor directly related to graphene quality, along with the gas ratio being a factor directly proportional to the success of the synthesis (LI, 2016).

[0011] The synthesis of graphene was divided into the following steps: 1. Cleaning and preparing the chamber and substrate; 2. Plasma cleaning of the sample and chamber with Hydrogen and Argon; 3. Addition of methane to the gas mixture and commencement of synthesis; 4. Plasma shutdown and system depressurization with Argon for inert gas cooling; 5. Removal of the substrate containing graphene. The parameters for stage 2 were set according to Table 1, while the parameters for stage 3 are set according to Table 2. Table 1 Sample Number | Gas Ratio in Cleaning (Gases Used) | Cleaning Pressure | Cleaning Temperature | Time | 1 | 1:1 (Air:H2) | 1.5 mBar | 500°C | 5 min | 2 | 1:1 (Air:H2) | 1.5 mBar | 500°C | 5 min | 3 | 1:1 (Air:H2) | 2.7 mBar | 500°C | 5 min | 4 | 1:1 (Air:H2) | 1.3 mBar | 500°C | 5 min | 5 | 1:1 (Air:H2) | 1.3 mBar | 500°C | 5 min | 6 | 1:1 (Air:H2) | 2.4 mBar | 500°C | 5 min | Petition 870240111270, dated 12 / 30 / 2024, page 9 / 17 / 5 Table 2 Sample Number | Gas Ratio in Synthesis (Gases Used) | Pressure in Synthesis | Temperature in Synthesis | Time | 1 | 10:10:1 (Ar:H2:CH4) | 1.7 mBar | 500°C | 10 min | 2 | 10:10:1 (Ar:H2:CH4) | 1.7 mBar | 500°C | 10 min | 3 | 10:10:1 (Ar:H2:CH4) | 3 mBar | 600°C | 10 min | 4 | 5:5:1 (Ar:H2:CH4) | 1.7 mBar | 500°C | 10 min | 5 | 5:5:1 (Ar:H2:CH4) | 1.7 mBar | 550°C | 10 min | 6 | 5:5:1 (Ar:H2:CH4) | 3 mBar | 600°C | 10 min |

[0012] After synthesis, the substrates were sent for Raman analysis, with the aim of characterizing the graphene samples and analyzing their quality and parameters, based on bibliographic data. With the produced graphene and its parameters analyzed and improved, its application in the APL for research and applications will be possible, in addition to publications and dissemination about the graphene produced in PECVD and its respective parameters.

[0013] The plasma chamber was produced with the gas outlet exiting through a gas shower, with the aim of distributing the gases more uniformly over the copper samples (1)(2). The chamber is cleaned with acetone and subsequently with hydrogen plasma at 2 mBar. The copper samples are cleaned with acetone (3) and cut into a 2.5x2.5cm square. Petition 870240111270, dated 12 / 30 / 2024, page 10 / 17 / 5

[0014] With the 12 samples prepared together with the chamber, the substrate cleaning (4) and synthesis are carried out, with 2 copper samples for each parameter. Λ — I - I .·!· I < - I — — —--2 —. The initial vacuum pressure used in the samples is 8.5 x 10 mBar.

[0015] After cleaning and synthesizing (5), the samples are separated and stored with their respective parameters. References

[0016] CAMARGOS, JSF & SEMMER, AO & SILVA, SN CHARACTERISTICS AND APPLICATIONS OF GRAPHENE AND GRAPHENE OXIDE AND THE MAIN ROUTES FOR SYNTHESIS. The Journal of Engineering and Exact Sciences, V.3, n.8, p. 1118-1130, 2017.

[0017] LI, Menglin et al. Controllable Synthesis of Graphene by Plasma-Enhanced Chemical Vapor Deposition and Its related Applications. Advanced Science, V. 3, n. 11, 2016.

[0018] SHARBIDRE, Rakesh et al. Comparison of Existing Methods to Identify teh Number of Graphene Layers. Korean Journal of Materials Research. V. 26, pg. 704 to 708, 2016.

[0019] WOEHRL, Nicolas et al. Graphene plasma-enhanced chemical vapor deposition on copper substrates. AIP Advances, V. 4. 2014. Petition 870240111270, dated 12 / 30 / 2024, p. 11 / 17

Claims

CLAIMS 1. Process for Graphene Synthesis by Plasma Enhanced Vapor Deposition with Direct Current Source characterized by being divided into the following steps: (a) Cleaning and preparation of the chamber and substrate; (b) Plasma cleaning of the sample and chamber with Hydrogen and Argon; (c) Addition of methane to the gas mixture and start of the synthesis; (d) Plasma shutdown and depressurization of the system with Argon for cooling with inert gas; (e) Removal of the substrate with graphene. Petition 870240111270, dated 12 / 30 / 2024, page 12 / 17

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