Graphene Induced Diamond Nucleation on Tungsten
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-01-01 |
| Journal | IEEE Open Journal of Nanotechnology |
| Authors | Yonhua Tzeng, C. S. Chang |
| Institutions | National Cheng Kung University |
| Citations | 5 |
| Analysis | Full AI Review Included |
Graphene Induced Diamond Nucleation on Tungsten: Technical Analysis and 6CCVD Solutions
Section titled âGraphene Induced Diamond Nucleation on Tungsten: Technical Analysis and 6CCVD SolutionsâThis document analyzes the research detailing a novel chemical vapor deposition (CVD) method for diamond nucleation using monolayer graphene on tungsten (W) thin films, and outlines how 6CCVDâs advanced MPCVD diamond materials and engineering services can support and extend this breakthrough research.
Executive Summary
Section titled âExecutive Summaryâ- Novel Nucleation Mechanism: The research successfully demonstrates a chemical nucleation method for continuous CVD diamond films using the etched edges of monolayer graphene on a tungsten (W) thin film, eliminating the need for traditional diamond seeding or Bias Enhanced Nucleation (BEN).
- High Nucleation Density: The process achieved an equivalent diamond nucleation density estimated at 1010 cm-2, resulting in continuous polycrystalline diamond (PCD) films with small grain sizes (< 1 ”m).
- Interface Chemistry: Nucleation is proposed to be assisted by the formation of stable sp3 C-W bonds at the graphene edges, converting the 2-D graphene structure into a 3-D carbon structure favorable for diamond growth.
- Scalable Method: The diamond films were grown using standard Microwave Plasma CVD (PECVD) at 915 MHz and 50 Torr, suggesting potential for large-area industrial application.
- Density Control: Nucleation density was shown to be controllable and increased directly with the number of randomly stacked monolayer graphene layers (up to 4 layers tested).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results and methodology sections of the paper:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Equivalent Diamond Nucleation Density | 1010 | cm-2 | Based on 0.1 ”m spacing between nuclei (Fig. 2C) |
| Continuous Film Nucleation Density | > 108 | cm-2 | Based on average grain size < 1 ”m |
| CVD Plasma Frequency | 915 | MHz | Microwave Plasma CVD (MPCVD) excitation |
| Microwave Power Range | 3000 - 6000 | W | Applied power range at 915 MHz |
| CVD Gas Pressure | 50 | Torr | Operating pressure for nucleation and growth |
| Substrate Temperature (Plasma On) | 950 | °C | Measured during diamond growth |
| Methane Concentration (Nucleation/Growth) | 1 - 3 | % | Diluted in 97-99% H2 (or H2/Ar mixture) |
| Diamond Film Growth Duration | 4 | hr | Used to achieve continuous films |
| Resulting Diamond Raman Peak | 1334 | cm-1 | Shifted 2 cm-1 from standard 1332 cm-1 due to stress |
| Tungsten Sputtering RF Power | 30 - 200 | W | Applied at 13.56 MHz |
Key Methodologies
Section titled âKey MethodologiesâThe experiment utilized a multi-step process involving thermal CVD, RF sputtering, and MPCVD:
- Graphene Synthesis: Monolayer graphene was synthesized via low-pressure thermal CVD using methane diluted by hydrogen and argon on copper foils at 1040 °C.
- Tungsten Thin Film Deposition: A Tungsten (W) thin film was deposited onto a SiO2/Si substrate using RF magnetron sputtering in argon gas (< 30 mTorr), with RF power ranging from 30 W to 200 W.
- Graphene Transfer: Monolayer graphene was transferred from the copper foil to the W-coated SiO2/Si substrate. Random stacking of up to four layers was performed to increase edge density.
- Diamond Nucleation and Growth (MPCVD):
- The W/Graphene/SiO2/Si substrate was exposed to a microwave plasma (915 MHz, 3000-6000 W) at 50 Torr.
- The gas mixture consisted of 1% to 3% CH4 diluted primarily in H2.
- The process relies on atomic hydrogen etching the graphene to create reactive edges, followed by chemical reaction with W to form sp3 C-W bonds, initiating diamond nucleation.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research demonstrates a highly effective, non-traditional method for achieving high-density diamond nucleation, which is crucial for producing smooth, continuous polycrystalline diamond (PCD) films. 6CCVD is uniquely positioned to support the replication and scaling of this technology through its specialized MPCVD material supply and custom engineering services.
| Research Requirement/Challenge | 6CCVD Solution & Capability | Technical Advantage |
|---|---|---|
| High-Density Polycrystalline Diamond (PCD) | PCD Wafers and Plates: Custom dimensions up to 125mm diameter. Thicknesses from 0.1 ”m to 500 ”m. | Enables the deposition of continuous, pinhole-free diamond films over large areas, essential for scaling this nucleation technique to industrial substrates. |
| Substrate Interface Engineering (W/Graphene) | Custom Metalization Services: Internal capability for depositing Tungsten (W), Titanium (Ti), Platinum (Pt), Palladium (Pd), and Gold (Au). | Researchers can precisely replicate the critical W thin film layer, or explore alternative carbide-forming metals (like Ti or Mo) mentioned in related studies, directly on 6CCVD-supplied substrates. |
| Substrate Material Flexibility | SCD, PCD, and BDD Substrates: Substrate thickness up to 10 mm. | Provides high-purity diamond materials for use as reference layers, or for complex heterostructures where diamond is grown on diamond (homoepitaxy) after initial heterogeneous nucleation. |
| Surface Quality for Graphene Transfer | Advanced Polishing Services: Polishing for inch-size PCD achieving surface roughness Ra < 5 nm. | Ensures optimal surface preparation for subsequent graphene transfer and stacking, minimizing defects that could interfere with the edge-line nucleation mechanism. |
| Process Optimization & Scaling | In-House PhD Engineering Support: Consultation on material selection, plasma compatibility, and interface chemistry for novel CVD processes. | Our expert team can assist in optimizing the CH4/H2 ratio and power density parameters to maximize the sp3 C-W bond formation and nucleation yield for specific applications. |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Chemical vapor deposition (CVD) of a diamond film on a non-diamond substrate begins with the insertion of diamond seeds or the formation of diamond nuclei on the substrate. For the deposition of a smooth, large-area and pin-hole free diamond film that adheres well to the substrate, diamond seeds or nuclei need to be of high density, uniformly distributed and adhere well to the substrate. Diamond seeding is not a diamond nucleation process. Bias enhanced nucleation (BEN) is the most effective means of heterogeneous nucleation of diamond for CVD diamond. It is based on a negative biasing voltage between the substrate and the diamond CVD plasma to accelerate positive ions from the plasma to bombard the substrate. Both direct diamond seeding and BEN have technical barriers in practical applications. New diamond nucleation techniques are desired. This paper reports novel heterogenous diamond nucleation along edge line of graphene on tungsten leading to the deposition of continuous diamond films. Based on experimental observation, a diamond nucleation mechanism assisted by sp3 C-W bonds at graphene edge is proposed. It is wished that scientists will become interested in revealing the precise diamond nucleation mechanism. With that, further optimization of this invention may lead to a new, complementary diamond nucleation process for practical deposition of diamond films.