Effect of Boron Doping on Diamond Film and Electrochemical Properties of BDD According to Thickness and Morphology

At a Glance

Metadata	Details
Publication Date	2020-03-30
Journal	Coatings
Authors	Chang Song, Dae‐Seung Cho, Jae‐Myung Lee, Pung Keun Song
Institutions	Pusan National University
Citations	19
Analysis	Full AI Review Included

Technical Analysis and Documentation: Boron-Doped Diamond (BDD) for Electrochemical Applications

Prepared by: 6CCVD Technical Sales Engineering Team Reference Paper: Effect of Boron Doping on Diamond Film and Electrochemical Properties of BDD According to Thickness and Morphology

Executive Summary

This study successfully demonstrates the synthesis and characterization of high-quality Boron-Doped Diamond (BDD) films via Hot-Filament Chemical Vapor Deposition (HFCVD) optimized for electrochemical applications.

Cost-Effective Synthesis: Achieved BDD deposition on low-cost Titanium (Ti) substrates by incorporating a crucial Niobium (Nb) interlayer buffer layer (3 µm thick) to mitigate thermal expansion mismatch and substrate bending.
Controlled Doping: Boron doping was successfully confirmed via Raman spectroscopy, reaching a calculated concentration of 7902 ppm (B/C ratio of 0.007902).
Consistent Growth Rate: A stable average deposition rate of 100 nm/h was maintained over runs spanning up to 60 hours, resulting in thicknesses up to 5.91 µm.
Improved Electrochemical Performance: The potential window of the BDD films increased significantly with thickness (from 1.22 µm to 5.91 µm), essential for high-performance electrode applications.
Quality Advantage: The methodology focused on temperature control during deposition to prevent amorphous carbonization, resulting in BDD electrodes with superior intrinsic electrochemical activation and catalytic activity compared to the reference material.
Application Focus: The synthesized BDD films demonstrate high suitability for use as advanced, insoluble electrodes in wastewater treatment and highly sensitive sensor technology.

Technical Specifications

The following hard data points were extracted from the HFCVD and HiPIMS experimental parameters:

Parameter	Value	Unit	Context
Target Doping Concentration (B/C)	7902	ppm	Calculated from acetone and TMB flux ratios (0.007902)
Average BDD Deposition Rate	100	nm/h	Consistent average rate across 12 h and 60 h runs
Maximum BDD Thickness Achieved	5.91	µm	Thickness after 60 h deposition
Substrate Stack	Ti / Nb (3 µm) / BDD	Material / Thickness	Ti used for cost reduction; Nb used for stress relief
Nb Interlayer Thickness	3	µm	Deposited via HiPIMS to buffer thermal stress
HFCVD Filament Power	16	kW	Applied to 12 Tantalum filaments (0.7 mm thick)
HFCVD Working Pressure	4000	Pa	Optimal pressure identified from prior studies
Filament-Susceptor Distance	10	mm	Optimized working distance for temperature profile
Primary Electrolyte (CV)	0.5 M Na₂SO₄	Concentration	Used to measure the potential window
Reference Electrode	Ag/AgCl	N/A	Used during cyclic voltammetry (CV) measurement

Key Methodologies

The experiment combined two distinct thin-film deposition techniques: HiPIMS for the intermediate layer and HFCVD for the final BDD film.

Substrate & Interlayer Coating (HiPIMS): Titanium (Ti) plates (1 mm thick) were selected as the primary, low-cost substrate. A columnar Niobium (Nb) interlayer, 3 µm thick, was deposited onto the Ti via High-Power Impulse Magnetron Sputtering (HiPIMS) over 1 hour at 100 °C to prevent high-temperature bending caused by the thermal expansion mismatch between Ti and diamond.
Diamond Seeding: Substrates underwent mechanical pretreatment using a 500 nm diamond particle powder mixed with glycerin (1:1 weight ratio) to ensure robust nucleation sites for subsequent CVD growth.
HFCVD Setup: Deposition was carried out using 12 Tantalum (Ta) filaments in a HFCVD system, maintaining a fixed distance of 10 mm between the filament and the rotating susceptor.
Gas Precursors & Doping: Acetone (C₃H₆O₆) was used as the primary carbon source (90 sccm), and Trimethyl Borate (TMB, C₃H₉O₃B) was used as the boron and supplementary carbon source (6 sccm). Both precursors were delivered via a bubbling system temperature-controlled precisely at 0 °C. Hydrogen flow was maintained at 400 sccm.
Growth Strategy: Films were grown for 12 hours and 60 hours. A focus was placed on precise temperature control during deposition to prevent the formation of amorphous carbon (graphitic non-diamond phases), which significantly degrades electrochemical performance.
Electrochemical Analysis: Cyclic voltammetry (CV) curves were measured using a Pt counter electrode and an Ag/AgCl reference electrode to assess the BDD films’ potential window and their electrochemical activation/catalytic activity in Na₂SO₄ and K₃Fe(CN)₆/K₄Fe(CN)₆ solutions.

6CCVD Solutions & Capabilities

6CCVD’s specialized MPCVD synthesis capabilities are optimally suited to replicate, scale, and significantly enhance the BDD electrode manufacturing process outlined in this research, offering superior material quality and customization.

Applicable Materials & Quality Enhancement

Research Requirement	6CCVD Material Recommendation	Technical Advantage & Sales Driver
Boron-Doped Electrodes	Heavy Boron Doped Polycrystalline Diamond (PCD/BDD)	6CCVD offers doping concentration optimization across a wide range, allowing precise control of carrier density for specific electrochemical applications (e.g., maximizing hydroxyl radical generation).
Quality Control (Preventing Amorphous Carbonization)	MPCVD vs. HFCVD Advantage	Unlike the HFCVD method used, 6CCVD utilizes highly controlled Microwave Plasma CVD (MPCVD). MPCVD inherently delivers a higher quality film with far less non-diamond carbon content (e.g., amorphous carbon or graphite), leading to larger potential windows and superior stability.
Electrochemical Surface Finish	PCD Polishing Service	While the paper utilizes as-grown morphology, 6CCVD offers precision polishing (Ra < 5 nm for inch-size PCD) for applications requiring ultra-smooth surfaces, such as microelectrode arrays or advanced sensor development.

Customization Potential & Engineering Support

Paper Requirement	6CCVD Custom Capability	Sales Driver & Call to Action
Complex Substrate Stack (Ti/Nb Interlayer)	Custom Metalization & Interlayer Deposition	We offer comprehensive internal metalization services, including Ti, W, Au, Pt, Pd, and Cu. We can deposit the necessary Nb interlayer or alternative stress-mitigating layers (such as W or Ta) onto custom substrates (e.g., Ti) before diamond growth, ensuring optimal adhesion and thermal stability.
Scalability (3 cm x 3 cm used)	Large Area Diamond Wafers	6CCVD produces high-quality PCD/BDD wafers up to 125 mm (5 inches) in diameter, allowing for seamless scaling of this research from R&D coupon size to industrial electrode dimensions.
Precise Thicknesses (1.22 µm to 5.91 µm)	Precision Thickness Control	Our MPCVD systems provide repeatable, uniform thickness control for BDD films from 0.1 µm up to 500 µm, meeting the precise film thickness targets required for maximizing electrochemical efficiency.
Material Selection & Process Optimization	In-house PhD Engineering Support	6CCVD’s team of PhD material scientists can consult on optimizing precursor selection, gas flow ratios, and temperature profiles specifically for similar BDD-based water treatment or electroanalysis projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Diamond coating using hot-filament chemical vapor deposition (HFCVD) is now widely used in many fields. The quality of the diamond film and many factors determine the success of the coating, such as temperature, time, and pressure during coating. The purpose of this study was to produce coated boron-doped diamond (BDD) films by doping boron in the diamond film and to assess them through comparative analysis with foreign acid BDD, which is widely used as a water-treatment electrode in the present industry. The bending of the titanium substrate due to the high temperature during the diamond deposition was avoided by adding an intermediate layer with a columnar structure to niobium film. The filament temperature and pressure were determined through preliminary experiments, and BDD films were coated. The BDD film deposition rate was confirmed to be 100 nm/h, and the potential window increased with increasing thickness. The electrochemical activation and catalytic performance were confirmed according to the surface characteristics. Although the high deposition rate of the BDD coating is also an important factor, it was confirmed that conducting coating so that amorphous carbonization does not occur by controlling the temperature during coating can improve the electrochemical properties of BDD film.

Tech Support

Original Source

DOI: https://doi.org/10.3390/coatings10040331

References

1990 - The Effect of Oxygen in Diamond Deposition by Microwave Plasma Enhanced Chemical Vapor-Deposition [Crossref]
1991 - Noble-Gas Studies in Vapor-Growth Diamonds—Comparison with Shock-Produced Diamonds and the Origin of Diamonds in Ureilites [Crossref]
1992 - Hot Filament Assisted Deposition of Silicon-Nitride Thin-Films [Crossref]
1994 - Temperature-Dependence of Growth-Rate for Diamonds Grown Using a Hot-Filament Assisted Chemical-Vapor-Deposition Method at Low Substrate Temperatures [Crossref]
1996 - Lattice disorder and texture in diamond coatings deposited by HFCVD on Co-cemented tungsten carbide [Crossref]
2017 - Boron doped diamond electrooxidation of 6:2 fluorotelomers and perfluorocarboxylic acids. Application to industrial wastewaters treatment [Crossref]
2014 - Electrochemical treatment of artificial humidity condensate by large-scale boron doped diamond electrode [Crossref]
2007 - Studies on electrochemical treatment of wastewater contaminated with organotin compounds [Crossref]
2012 - Synthesis and Temperature-dependent Electrochemical Properties of Boron-doped Diamond Electrodes on Titanium
2009 - Electrochemical disinfection of biologically treated wastewater from small treatment systems by using boron-doped diamond (BDD) electrodes - Contribution for direct reuse of domestic wastewater [Crossref]