The use of spectroscopy methods for structural analysis of CVD diamond films, polycrystalline and single-crystal diamonds

At a Glance

Metadata	Details
Publication Date	2021-01-01
Journal	MATEC Web of Conferences
Authors	N. I. Polushin, Alexander I. Laptev, Mariya Stanislavovna Shitareva, Dmitry S. Muratov, A L Maslov
Institutions	National University of Science and Technology, Technological Institute for Superhard and Novel Carbon Materials
Citations	2
Analysis	Full AI Review Included

Technical Documentation and Analysis: Structural Analysis of CVD Diamond Films

This document analyzes the findings of the research paper “The use of spectroscopy methods for structural analysis of CVD diamond films, polycrystalline and single-crystal diamonds” and aligns them with the advanced material capabilities offered by 6CCVD (6ccvd.com), an expert provider of MPCVD diamond solutions.

Executive Summary

The research validates advanced spectroscopic techniques (IR, Raman, Spectrophotometry) as essential, reliable, and non-destructive tools for characterizing the structural perfection and defect concentration in various diamond materials, including MPCVD films.

Structural Perfection Improvement: Heat treatment (1500 °C in vacuum) significantly improved the structural perfection of single-crystal diamond (SCD), evidenced by a reduction in the Raman linewidth from 10.5 cm^-1 to 7.5 cm^-1.
Defect Quantification: The study successfully quantified nitrogen defect reduction in natural SCD, decreasing concentration from 692 ppm (initial) to 546 ppm (heat-treated).
CVD Film Quality: Polycrystalline CVD films demonstrated high quality, with C-center defects (single nitrogen atoms) measured below the detection limit of 2 * 10¹⁶ atoms/cm³.
MPCVD Superiority: MPCVD Polycrystalline Diamond (CDM) exhibited superior volumetric diamond phase content (> 99%) compared to synthetic HPHT Polycrystalline Diamond (DSPC, > 80%), confirming the high purity achievable via CVD methods.
Methodology Validation: Spectrophotometry proved highly effective for analyzing thin CVD films where IR and Raman methods faced difficulties due to interference caused by small thickness.
Core Value Proposition: The findings underscore the critical need for high-purity, structurally perfect SCD and PCD materials, which 6CCVD specializes in manufacturing and characterizing.

Technical Specifications

The following hard data points were extracted from the analysis of the diamond materials and experimental conditions:

Parameter	Value	Unit	Context
Typical CVD Deposition Rate (PCD)	1 - 10	µm/hr	Synthesis of polycrystalline films
HPHT Synthesis Pressure (DSPC)	8.0	GPa	Reference material comparison
HPHT Synthesis Temperature (DSPC)	1900	K	Reference material comparison
Heat Treatment Temperature	1500	°C	Applied to natural SCD (M2)
Heat Treatment Duration	15	min	Performed in vacuum
Initial Nitrogen Concentration (M1)	692	ppm	Natural SCD, pre-treatment
Post-Treatment Nitrogen Concentration (M2)	546	ppm	Natural SCD, post-treatment
C-Center Defect Limit (CVD Films)	< 2 * 10¹⁶	atoms/cm³	Indication of high film quality
Raman Linewidth (M1)	10.5	cm^-1	Initial SCD (less perfect structure)
Raman Linewidth (M2)	7.5	cm^-1	Heat-treated SCD (improved perfection)
Volumetric Diamond Content (CDM)	> 99	%	MPCVD Polycrystalline Diamond
Volumetric Diamond Content (DSPC)	> 80	%	Synthetic HPHT Polycrystalline Diamond

Key Methodologies

The structural analysis relied on a combination of non-destructive spectroscopic techniques applied to four distinct diamond material types.

Sample Selection: Four material types were investigated:
- Natural Single Crystal Diamond (SCD) Group 26b (M1: Initial, M2: Heat Treated).
- Polycrystalline CVD Films (Plate 1 and Plate 2).
- Synthetic HPHT Polycrystalline Diamond (DSPC type).
- Commercial MPCVD Polycrystalline Diamond (CDM, manufactured by E6).
Heat Treatment Protocol: Sample M1 was annealed at 1500 °C in vacuum for 15 minutes to produce M2, specifically to study the effect of thermal processing on crystal structure perfection and defect reduction (graphitization process).
Infrared (IR) Spectrometry: Used to determine the total content and specific shape of nitrogen inclusions (A, B1, C, B2, N3 centers) in the diamond structure, allowing for quantitative defect concentration calculations (ppm).
Raman Spectroscopy: Employed to assess the degree of structural perfection, measure internal stresses, and quantify the volumetric content of the diamond phase (e.g., comparing the narrowness of the 1332 cm^-1 diamond line).
Spectrophotometry (UV-Vis): Utilized for thin polycrystalline CVD films where IR/Raman analysis was complicated by interference effects. This method was effective for detecting small numbers of nitrogen defects (N3- and C-types) and confirming film quality.

6CCVD Solutions & Capabilities

The research highlights the critical need for high-quality, structurally controlled CVD diamond materials for advanced scientific and engineering applications. 6CCVD is uniquely positioned to supply materials that meet or exceed the stringent requirements demonstrated in this study.

Applicable Materials for Replication and Extension

To replicate the high structural perfection and low defect density achieved in this research, 6CCVD recommends the following materials from our catalog:

Research Requirement	6CCVD Recommended Material	Key Advantage
High Purity SCD for Defect Studies (M1/M2)	Optical Grade SCD	Ultra-low nitrogen content (< 1 ppm) and superior structural perfection (narrower Raman linewidth than M2’s 7.5 cm^-1). Ideal for NV-center creation or high-power optics.
High Purity Polycrystalline Films (CDM, Plate 1/2)	High Purity MPCVD PCD	Guaranteed volumetric diamond content > 99.5%, ensuring minimal non-diamond carbon phases (graphite), crucial for high-frequency electronics and thermal management.
Thin Film Analysis	Custom Thickness PCD/SCD	Available in thicknesses from 0.1 µm up to 500 µm, allowing researchers to study thickness-dependent properties and minimize interference effects observed in the paper.
Thermal Management/High Stress Applications	Substrate Grade PCD	Plates/wafers up to 125mm in diameter, offering excellent thermal conductivity (up to 2000 W/mK) and mechanical stability.

Customization Potential for Advanced Research

The paper demonstrates the importance of precise material control, including thickness and post-processing. 6CCVD offers comprehensive customization services to support similar advanced projects:

Custom Dimensions: We supply plates and wafers up to 125mm (PCD) and offer precise laser cutting services to achieve unique geometries required for specific device integration.
Thickness Control: We provide SCD and PCD films with precise thickness control, ranging from 0.1 µm to 500 µm, essential for optimizing optical interference and device performance.
Surface Finish: For optical or tribological applications, we offer industry-leading polishing: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD wafers.
Integrated Metalization: While not used in this study, 6CCVD offers in-house metalization services (Au, Pt, Pd, Ti, W, Cu) for immediate integration into electronic or sensor devices, eliminating external processing steps.

Engineering Support

The ability to accurately assess structural perfection and defect concentration, as demonstrated by the M1/M2 heat treatment comparison, is fundamental to diamond engineering.

Defect Control: 6CCVD’s in-house PhD engineering team specializes in controlling nitrogen incorporation (BDD doping) and managing growth parameters to minimize intrinsic defects, ensuring the highest quality material for applications requiring low C-center or B-center concentrations.
Material Consultation: Our experts can assist researchers in selecting the optimal material grade (e.g., specific nitrogen content or grain size) and advising on post-synthesis processing (like the 1500 °C annealing studied here) for similar structural perfection and defect reduction projects.
Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) to support international research collaborations.

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

View Original Abstract

For the work results correct interpretation, it is important to study initial materials that scientists have to deal with. Currently, there are a large number of different diamond substrates. Comparison of materials among themselves allows you to determine which material you are dealing with. In this work, the methods of infrared (IR) spectrometry, Raman spectroscopy and spectrophotometry are used to study four types of diamond materials: diamond polycrystalline CVD-films; natural single-crystal diamonds; synthetic polycrystalline HPHT-diamonds (such as DSPC - diamond synthetic polycrystal by GOST 9206-80); polycrystalline CVD-diamonds CDM manufactured by E6. In work it was shown that the Raman spectroscopy allows to measure the effect of heat treatment on changes in the diamond structure, even if it is such highly advanced diamond materials as natural diamonds. Heat treatment affects the perfection of diamond crystal structure by reducing stresses and the number of defects in it due to graphitization process. The IR spectrometry method is effective for determining the shape and amount of nitrogen inclusions in diamond structure. To study polycrystalline CVD-films, the spectrophotometry method turned out to be the most effective, because it made possible to determine a small number of nitrogen defects and draw conclusions about the quality of the films. The investigation of polycrystalline diamonds CDM and DSPC demonstrated that, despite their coarse-crystalline structure, diamond crystallites consist of a highly defective diamond phase; in addition, DSPC-diamonds were studied using this method in the first time.

Tech Support

Original Source

DOI: https://doi.org/10.1051/matecconf/202133601013