Effect of Boron Doping Concentration on the Wettability and Surface Free Energy of Polycrystalline Boron-Doped Diamond Film

At a Glance

Metadata	Details
Publication Date	2023-01-29
Journal	Coatings
Authors	Peng Wang, Qiyuan Yu, Xiaoxi Yuan, Zheng Cui, Yaofeng Liu
Institutions	Jilin Engineering Normal University, Jilin University
Citations	1
Analysis	Full AI Review Included

Technical Documentation & Analysis: Boron-Doped Diamond Wettability

This documentation analyzes the research on the effect of boron doping concentration on the wettability and Surface Free Energy (SFE) of Polycrystalline Boron-Doped Diamond (PBDD) films, linking the findings directly to 6CCVD’s advanced MPCVD capabilities.

Executive Summary

This study successfully demonstrates the precise control of surface free energy (SFE) in Polycrystalline Boron-Doped Diamond (PBDD) films through the adjustment of boron doping concentration via Microwave Plasma Chemical Vapor Deposition (MPCVD).

Material Focus: Polycrystalline Boron-Doped Diamond (PBDD) films were grown using 2.45 GHz MPCVD on abraded silicon wafers.
Key Finding: Surface Free Energy (SFE) reliably increases with increasing boron doping concentration (from B-01 to B-50).
SFE Range: Reliable SFE values ranged from 42.89 mJ/m² to 52.26 mJ/m², depending on the estimation approach used (Lifshitz-van der Waals/acid-base).
Morphology Consistency: Despite varying doping levels, the films maintained highly uniform surface morphology and roughness (Root-Mean-Square Roughness, Rq, remained stable between 128.89 nm and 131.13 nm).
Method Validation: The investigation validated the Owens-Wendt-Kaelble and Lifshitz-van der Waals/acid-base approaches as suitable for estimating PBDD film SFE, providing critical reference data for future surface science applications.
Application Relevance: The ability to tune SFE via doping is crucial for optimizing diamond coatings used in electrochemical sensing, adhesion, and anticorrosion applications.

Technical Specifications

Hard data extracted from the MPCVD process and characterization results.

Parameter	Value	Unit	Context
Deposition Method	MPCVD	N/A	Microwave Plasma Chemical Vapor Deposition
Microwave Frequency	2.45	GHz	Standard deposition frequency
Deposition Temperature	800	°C	Reaction chamber condition
Deposition Pressure	8.5	KPa	Reaction chamber condition
Deposition Time	11	h	Total growth duration
PBDD Film Thickness	~7	µm	Final approximate thickness
Substrate Pre-treatment	Abrasion	N/A	Diamond powder (~300 nm) used for nucleation
Roughness (Rq) Range	128.89 to 131.13	nm	Root-Mean-Square Roughness (Uniform across samples)
Lowest SFE (B-01)	42.89	mJ/m²	Lifshitz-van der Waals/acid-base approach
Highest SFE (B-50)	52.26	mJ/m²	Lifshitz-van der Waals/acid-base approach
Gas Ratio (B-01)	200/4/0.1	sccm	H₂/CH₄/Gas-B ratio (Lowest doping)
Gas Ratio (B-50)	200/4/5	sccm	H₂/CH₄/Gas-B ratio (Highest doping)

Key Methodologies

The experiment utilized precise MPCVD techniques and multi-liquid characterization to correlate boron concentration with surface properties.

Substrate Preparation: Silicon wafers were mechanically abraded using ~300 nm diamond powder to enhance surface roughness, promoting diamond nucleation.
Nucleation Seeding: Wafers were treated with an alcohol/diamond powder mixture in an ultrasonic cleaner for 60 minutes to maximize nucleation site density.
MPCVD Growth: PBDD films were deposited using a 2.45 GHz MPCVD system under controlled conditions (8.5 KPa, 800 °C).
Boron Doping Control: Gaseous boron (Gas-B, derived from trimethyl borate) was introduced, and the doping concentration was systematically varied by adjusting the H₂/CH₄/Gas-B flow ratios (e.g., 200/4/0.1 sccm for B-01 up to 200/4/5 sccm for B-50).
Morphological Analysis: SEM and AFM were used to confirm continuous film deposition and measure the uniform Rq roughness (128.89 nm to 131.13 nm).
Surface Chemistry Analysis: XRD confirmed crystalline composition and preferred (111) orientation. Raman spectroscopy confirmed the increase in boron-doping induced Fano effect and the downshift of the sp³ carbon peak due to tensile stress.
Wettability Measurement: Contact angles (CA) were measured using three probe liquids (DI water, diiodomethane, and glycerol) to enable SFE calculation via “three-liquids” methods (Lifshitz-van der Waals/acid-base).

6CCVD Solutions & Capabilities

This research highlights the critical need for highly controlled, customizable Boron-Doped Diamond (BDD) materials. 6CCVD is uniquely positioned to supply the materials and engineering support required to replicate, extend, and commercialize this research.

Research Requirement/Application	6CCVD Applicable Materials	6CCVD Customization Potential
Material: Polycrystalline Boron-Doped Diamond (PBDD) for electrochemical tuning.	Heavy Boron-Doped Diamond (BDD) / Polycrystalline Diamond (PCD)	We offer PCD wafers up to 125mm in diameter, providing scalability far beyond typical lab-scale samples.
Thickness Control: Precise 7 µm film required for specific device performance.	Custom Thickness Range	We guarantee precise thickness control for PCD films from 0.1 µm up to 500 µm, ensuring exact replication or optimization for specific device architectures.
Doping Uniformity: Need for repeatable, specific boron concentrations (B-01 to B-50).	Custom Doping Recipes & Certification	6CCVD specializes in tuning MPCVD gas flows to achieve specific, repeatable boron doping levels. We provide certified carrier concentration data to meet stringent electrochemical requirements (e.g., for supercapacitors or sensing devices).
Surface Finish: While the paper used rough films (Rq ~130 nm), many applications require ultra-smooth surfaces.	Advanced Polishing Services	We offer precision polishing down to Ra < 5 nm for inch-size PCD wafers, critical for micro-electro-mechanical systems (MEMS) and high-adhesion coatings.
Interfacial Engineering: Need to integrate diamond films into complex devices (e.g., sensors, transistors).	Custom Metalization Services	6CCVD offers in-house metalization capabilities, including Au, Pt, Pd, Ti, W, and Cu, allowing researchers to create functional contacts and device structures directly on the diamond film.
Global Supply Chain: Need for reliable, timely delivery of specialized materials.	Global Shipping Expertise	We provide global shipping (DDU default, DDP available) to ensure your research timeline is met, regardless of location.

Engineering Support

6CCVD’s in-house PhD team can assist with material selection and surface engineering for similar Electrochemical and Adhesion-Critical Diamond Coating projects. Our expertise ensures that the chosen diamond material (SCD, PCD, or BDD) and surface termination are optimized to achieve targeted wettability and SFE values, maximizing device performance and lifespan.

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

View Original Abstract

The wettability and surface free energy of diamonds are crucial for their applications. In this study, polycrystalline boron-doped diamond (PBDD) films with different boron doping concentrations were prepared, and the effect of the boron doping concentration on the wettability and surface free energy (SFE) of the film was investigated. The SFEs of the PBDD films were investigated by employing the surface tension component approach and the equation-of-state approach. The investigation suggested that the alternative formulation of Berthelot’s rule, the Lifshitz-van der Waals/acid-base (van Oss) approach, and the Owens-Wendt-Kaelble approach were suitable for estimating the SFEs of PBDD films, whereas the Fowkes approach, Berthelot’s (geometric mean) combining rule, and Antonow’s rule could not provide reliable results. Results showed that the SFEs of PBDD films increased with increasing boron doping concentration, and the SFEs were 43.26-49.66 mJ/m2 (Owens-Wendt-Kaelble approach), 42.89-52.26 mJ/m2 (Lifshitz-van der Waals/acid-base), and 44.38-48.73 mJ/m2 (alternative formulation of Berthelot’s rule). This study also provides a reference for the application of empirical and physics-based semi-empirical approaches to SFE estimation.

Tech Support

Original Source

DOI: https://doi.org/10.3390/coatings13020305

References

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