Near-Edge X-ray Absorption Fine-Structure Study on Hydrogenated Boron-Doped Ultrananocrystalline Diamond/Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-01-01 |
| Journal | Transactions of the Materials Research Society of Japan |
| Authors | YĹŤki Katamune, Satoshi Takeichi, Shinya Ohmagari, Hiroyuki Setoyama, Tsuyoshi Yoshitake |
| Institutions | SAGA Light Source, Synchrotron Light Research Institute |
| Citations | 6 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Hydrogenation Control in Boron-Doped Diamond Films
Section titled âTechnical Documentation & Analysis: Hydrogenation Control in Boron-Doped Diamond FilmsâThis document analyzes the research paper âNear-Edge X-ray Absorption Fine-Structure Study on Hydrogenated Boron-Doped Ultrananocrystalline Diamond/Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Depositionâ to provide technical specifications and highlight how 6CCVDâs advanced MPCVD diamond materials and customization services can replicate, optimize, and scale this research.
Executive Summary
Section titled âExecutive SummaryâThe research demonstrates precise control over the electrical properties of boron-doped diamond composite films by manipulating the hydrogen atmosphere during deposition. This work is highly relevant to engineers developing next-generation diamond-based electronic and sensing devices.
- Core Achievement: Successfully tuned B-doped UNCD/a-C:H films from a highly conductive semimetallic state to a semiconducting state by increasing hydrogen pressure.
- Mechanism Confirmed: NEXAFS analysis proved that atomic hydrogen preferentially etches sp²-bonded carbon (amorphous phase), which acts as the primary source of carriers in the semimetallic films.
- Electrical Transition: Conductivity decreased by approximately two orders of magnitude (from ~10Âł S/cm to ~10š S/cm) as Hâ pressure increased from 0 Pa to 6.7 Pa.
- Transport Physics: Highly hydrogenated films (26.7 Pa) exhibited typical semiconducting behavior where carrier transport followed three-dimensional Variable Range Hopping (VRH, m=4).
- Doping Stability: Boron content (3-4 at.%) remained stable across all hydrogen pressures, confirming that structural changes (sp²/sp³ ratio) are the dominant factor controlling conductivity, not doping concentration.
- 6CCVD Value Proposition: 6CCVD offers highly controlled Boron-Doped Diamond (BDD) materials via MPCVD, providing superior purity and structural uniformity necessary to precisely engineer the sp³/sp² ratio for advanced electronic applications.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental section of the paper:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Film Thickness | 200 | nm | Deposited on Si and Quartz substrates |
| Substrate Temperature | 550 | °C | During Coaxial Arc Plasma Deposition (CAPD) |
| Target Composition | 5 | at.% | Boron-blended graphite target |
| Hydrogen Pressure Range | 0, 1.3, 6.7, 26.7 | Pa | Key variable for hydrogenation control |
| Arc Plasma Voltage | 100 | V | Applied to the arc plasma gun |
| Arc Discharge Repetition Rate | 5 | Hz | CAPD process parameter |
| Boron Content (Estimated) | 3 - 4 | at.% | Stable across all Hâ pressures |
| Conductivity (Non-Hâ) | ~10Âł | S/cm | Semimetallic behavior |
| Conductivity (Hâ 6.7 Pa) | ~10š | S/cm | Semiconducting behavior |
| Activation Energy (Ea) Range | 0.005 - 0.05 | eV | Estimated around room temperature |
| Carrier Transport Mechanism (6.7 Pa) | VRH (m=4) | N/A | Three-dimensional Variable Range Hopping |
| Ohmic Contact Material | Pd | N/A | Deposited by RF magnetron sputtering |
Key Methodologies
Section titled âKey MethodologiesâThe B-doped UNCD/a-C:H films were prepared and analyzed using the following sequence and parameters:
- Deposition System: Films were grown using Coaxial Arc Plasma Deposition (CAPD) utilizing a boron-blended graphite target (5 at.% B).
- Substrate Preparation: Films were deposited on both Si and quartz substrates simultaneously.
- Environmental Control: The chamber was evacuated to a base pressure of < 10-3 Pa before introducing hydrogen gas at controlled pressures (0, 1.3, 6.7, and 26.7 Pa).
- Process Conditions: Substrate temperature was maintained at 550 °C. Arc plasma was generated using 100 V applied voltage and a 5 Hz repetition rate.
- Electrical Characterization: Conductivity was measured via the van der Pauw method in the temperature range of 250 K to 500 K. Pd ohmic electrodes were sputtered onto the film surface.
- Structural Analysis (XPS/NEXAFS): X-ray Photoelectron Spectroscopy (XPS, Mg Kι line) was used to estimate boron content. Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectra were obtained in Total Electron Yield (TEY) mode using synchrotron radiation (Beamline 12, Kyushu Synchrotron Light Research Center) to investigate chemical bonding structures (sp²/sp³ ratio).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research underscores the critical need for precise control over the diamond microstructure and doping profile to achieve targeted electrical performance. 6CCVDâs MPCVD capabilities offer superior control and scalability compared to the CAPD method used in this study.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research into high-performance electronic devices requiring controlled conductivity and high purity, 6CCVD recommends the following materials:
| 6CCVD Material | Description & Application | Relevance to Research |
|---|---|---|
| Heavy Boron-Doped PCD | Polycrystalline Diamond (PCD) with high boron concentration (BDD). Offers high conductivity and excellent thermal management. | Ideal for scaling up the semiconducting/semimetallic transition observed, providing a robust, large-area platform (up to 125mm) for electrochemical or high-power electronic devices. |
| Boron-Doped SCD | Single Crystal Diamond (SCD) with controlled boron doping. Offers the highest purity and structural perfection (minimal grain boundaries). | Necessary for fundamental studies requiring minimal influence from amorphous carbon or grain boundaries, allowing researchers to isolate the effects of boron incorporation and hydrogen termination on the intrinsic diamond lattice. |
| Optical Grade SCD | High-purity, low-defect SCD. | Can be used as a high-quality, insulating substrate (up to 500 Âľm thick) for subsequent deposition of BDD layers, minimizing substrate interference seen with Si or quartz. |
Customization Potential
Section titled âCustomization PotentialâThe experimental requirements of this paperâspecifically the thin film thickness, use of specific metal contacts, and need for precise structural controlâare directly addressed by 6CCVDâs core capabilities:
- Thickness Control: The paper used 200 nm films. 6CCVD routinely supplies SCD and PCD films with thicknesses ranging from 0.1 Âľm up to 500 Âľm, allowing for precise replication of thin-film structures or the development of thicker, self-supporting substrates (up to 10 mm).
- Custom Dimensions: While the paper used small lab samples, 6CCVD can provide PCD plates/wafers up to 125mm in diameter, enabling industrial scaling of BDD electronic devices.
- Surface Finish: 6CCVD offers ultra-smooth polishing, achieving Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD. This is crucial for minimizing surface scattering and ensuring reliable contact deposition (like the Pd electrodes used here).
- Metalization Services: The paper utilized Pd ohmic contacts. 6CCVD offers internal metalization capabilities including Au, Pt, Pd, Ti, W, and Cu, allowing researchers to receive fully integrated, ready-to-use devices with custom contact geometries.
Engineering Support
Section titled âEngineering SupportâThe ability to precisely tune the electrical properties of diamond by controlling the sp²/spÂł ratio and hydrogenation state is a complex challenge. 6CCVDâs in-house PhD team specializes in optimizing MPCVD growth recipes to achieve specific structural and electrical outcomes. We can assist researchers working on similar semiconducting diamond electronics, deep UV photodetectors, or bio-sensing applications by providing expert consultation on:
- Optimizing boron doping profiles for specific conductivity targets.
- Selecting the ideal diamond grade (SCD vs. PCD) based on application requirements (e.g., thermal conductivity, grain boundary effects).
- Designing custom metalization schemes for reliable ohmic or Schottky contacts.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Boron-doped ultrananocrystalline diamond/amorphous carbon composite films were deposited in the hydrogen pressure range up to 26.7 Pa by coaxial arc plasma deposition with a boron-blended graphite target, and the effects of hydrogenation on the electrical properties and chemical bonding structures of the films were discussed by near-edge X-ray absorption fine structure (NEXAFS) studies. The electrical conductivity decreased with increasing hydrogen pressure. Whereas the nonhydrogenated films showed a semimetallic behavior in the temperature dependence of the electrical conductivity, the hydrogenated films exhibited semiconducting behavior. The boron content estimated from X-ray photoelectron spectroscopic measurements hardly changed with the hydrogen pressure. NEXAFS spectra showed that Ď* resonance related to sp2-bonded carbon is evidently enhanced with decreasing hydrogen pressure, which is accompanied by a selective etching of sp2 carbon. The results indicate that the carrier transports in UNCD/a-C films are strongly influenced by chemical bonding structure at a-C or grain boundaries.