Morphology and Structure Properties of Boron-doped Diamond Films Prepared by Hot Cathode Direct Current Plasma Chemical Vapor Deposition

At a Glance

Metadata	Details
Publication Date	2016-05-19
Journal	Materials Science
Authors	Mengmei Pan, Hongyan Peng, Wanbang Zhao, Hongwei Jiang
Institutions	Dalian University of Technology, Hainan Normal University
Analysis	Full AI Review Included

Technical Documentation & Analysis: Boron-Doped Diamond Films via HCDC-PCVD

6CCVD specializes in high-quality, scalable MPCVD diamond solutions, offering superior material purity and dimensional control compared to HCDC-PCVD methods.

Executive Summary

This research successfully demonstrates the fabrication and characterization of Boron-Doped Diamond (BDD) films using Hot Cathode Direct Current Plasma Chemical Vapor Deposition (HCDC-PCVD). The findings are highly relevant for engineers developing advanced electrochemical and electronic diamond applications.

Material Focus: Boron-Doped Diamond (BDD) films deposited on p-Si substrates, targeting applications requiring wide electrochemical potential and high corrosion stability.
Doping Control: Precise control of B-doping levels achieved by varying the Trimethyl Borate (B(OCH${3}$)${3}$) flow rate (0 to 20 sccm).
Achieved Doping Range: Doping levels spanned from the semiconducting regime (1.75 x 10¹⁹ cm^-3) up to the metallic conductivity regime (2.40 x 10²¹ cm^-3).
Structural Evolution: Increasing boron incorporation promoted the growth of the (110) diamond texture, diminished growth steps, and led to smoother, more symmetrical grain facets (2 µm to 5 µm size).
Film Dimensions: Films achieved thicknesses between 16 µm and 22 µm, corresponding to an average growth rate of 2-3 µm/hour.
Raman Confirmation: High boron content induced the characteristic asymmetric Fano-like line shape in the diamond peak, confirming the transition to metallic conductivity due to quantum interference.

Technical Specifications

The following hard data points were extracted from the HCDC-PCVD deposition process and resulting BDD film properties:

Parameter	Value	Unit	Context
Deposition Method	HCDC-PCVD	N/A	Hot Cathode Direct Current Plasma CVD
Substrate Material	p-Si	N/A	Used for BDD film deposition
Chamber Pressure	13	kPa	Constant operating pressure
DC Voltage Range	700 ~ 800	V	Plasma excitation range
DC Current Range	8 ~ 10	A	Plasma excitation range
Substrate Temperature	~800	°C	Maintained during growth
Growth Time	7.5	hour	Total deposition duration
CH$_{4}$ Flow Rate	4	sccm	Constant carbon source flow
H$_{2}$ Flow Rate	200	sccm	Constant carrier gas flow
B(OCH${3}$)${3}$ Flow Range	0 to 20	sccm	Boron source variation
Film Thickness Range	16 ~ 22	µm	Measured via cross-sectional SEM
Average Growth Rate	2 ~ 3	µm/hour	Deduced rate
Minimum B Doping Level	1.75 x 10¹⁹	cm^-3	Sample b (1 sccm B flux)
Maximum B Doping Level	2.40 x 10²¹	cm^-3	Sample e (10 sccm B flux)
Primary Grain Size	2 to 5	µm	Unaltered by B flow rate
Diamond Raman Peak	~1332	cm^-1	First-order Raman curve

Key Methodologies

The BDD films were prepared using a Hot Cathode Direct Current Plasma Chemical Vapor Deposition (HCDC-PCVD) system.

Chamber Preparation: A stainless steel chamber was evacuated to a base pressure of 10^-2 Pa.
Substrate Loading: p-Si substrates were used for deposition.
Gas Introduction: High purity CH${4}$ and H${2}$ were used as reactant gases. Trimethyl borate (B(OCH${3}$)${3}$) served as the boron source, introduced via bubbling H$_{2}$ gas.
Parameter Control: All depositions were conducted at a constant pressure of 13 kPa and a substrate temperature of approximately 800 °C.
Plasma Excitation: A DC power supply excited the plasma, operating between 700 V and 800 V, and 8 A to 10 A.
Doping Variation: The B(OCH${3}$)${3}$ flow rate was systematically varied (0, 1, 2, 5, 10, 20 sccm) while CH${4}$ (4 sccm) and H${2}$ (200 sccm) flows remained constant.
Characterization:
- Morphology/Thickness: Scanning Electron Microscopy (SEM, Hitachi S-4800) was used for top-view and cross-sectional analysis.
- Structural/Doping: Raman spectroscopy (Renishaw inVia, 514.5 nm argon ion laser) was used to analyze bonding, estimate B-doping concentration via the 500 cm^-1 peak shift, and confirm the Fano interference effect.

6CCVD Solutions & Capabilities

The research highlights the potential of heavily Boron-Doped Diamond (BDD) for electrochemical applications, requiring precise control over doping concentration and film quality. While HCDC-PCVD offers cost advantages, 6CCVD utilizes state-of-the-art Microwave Plasma Chemical Vapor Deposition (MPCVD) to deliver superior material quality, scalability, and customization necessary for commercial and advanced research applications.

Applicable Materials

To replicate or extend the metallic conductivity achieved in this study (2.4 x 10²¹ cm^-3), 6CCVD recommends the following materials:

6CCVD Material	Description & Relevance to Research	Key Specifications
Heavy Boron-Doped PCD (BDD-PCD)	Ideal for high-performance electrochemical electrodes and high-power electronics. We guarantee doping levels that achieve the metallic conductivity regime (Fano interference confirmed).	Doping up to 5 x 10²¹ cm^-3. Plates up to 125 mm diameter.
Lightly Doped BDD-SCD	For applications requiring semiconducting behavior, such as UV detectors or specific quantum sensing applications.	Doping range 10¹⁷ to 10¹⁹ cm^-3. High purity, low defect density.
Polycrystalline Diamond (PCD)	Used as a high-quality, thermally managed substrate or protective layer.	Thickness up to 500 µm. Polishing Ra < 5 nm (inch-size).

Customization Potential

The HCDC-PCVD process yielded films up to 22 µm thick. 6CCVD’s MPCVD capabilities offer significantly greater flexibility and scale:

Thickness Control: While the paper achieved 16-22 µm, 6CCVD offers BDD-PCD films up to 500 µm thick, suitable for robust, free-standing electrodes or heat spreaders.
Dimensional Scaling: We provide custom BDD plates and wafers up to 125 mm in diameter, far exceeding typical HCDC-PCVD limitations.
Surface Finish: We offer precision polishing services to achieve surface roughness (Ra) < 5 nm on inch-size PCD/BDD wafers, crucial for minimizing background current in sensitive electrochemical measurements.
Custom Metalization: For integrating BDD electrodes into devices, 6CCVD offers in-house metalization services, including standard contacts (Ti/Pt/Au) and custom stacks (Pd, W, Cu).

Engineering Support

The structural analysis in this paper focused on the transition from (111) to (110) texture and the resulting twinning bands. 6CCVD’s in-house PhD team specializes in optimizing diamond growth recipes to control crystal orientation and defect density.

Application Expertise: We provide material selection assistance for similar Electrochemical Sensing and Water Treatment projects, ensuring the BDD material meets specific conductivity and stability requirements.
Recipe Optimization: We can assist researchers in selecting the optimal doping level (e.g., metallic vs. semiconducting) required for specific device performance, moving beyond the empirical HCDC-PCVD methods described.

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

View Original Abstract

Boron-doped diamond (BDD) films were deposited by hot cathode direct current plasma chemical vapor deposition (HCDC-PCVD) according to various mixture…

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Original Source

DOI: https://doi.org/10.5755/j01.ms.22.2.12923