The use of spectroscopy methods for structural analysis of CVD diamond films, polycrystalline and single-crystal diamonds
At a Glance
Section titled âAt a Glanceâ| 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 |
The Use of Spectroscopy Methods for Structural Analysis of CVD Diamond Films, Polycrystalline and Single-Crystal Diamonds
Section titled âThe Use of Spectroscopy Methods for Structural Analysis of CVD Diamond Films, Polycrystalline and Single-Crystal DiamondsâExecutive Summary
Section titled âExecutive Summaryâ- Validated Methodology: A complex of non-destructive spectroscopic methods (IR spectrometry, Raman spectroscopy, and spectrophotometry) was established as a simple, reliable, and rapid technique for analyzing four distinct types of diamond materials.
- Structural Improvement via Heat Treatment: Heat treatment (1500 °C in vacuum) of natural single-crystal diamonds (M1) significantly increased structural perfection, evidenced by a reduction in the Raman line half-width from 10.5 cm-1 to 7.5 cm-1.
- Nitrogen Defect Quantification: IR spectrometry successfully determined nitrogen defect concentrations, showing a decrease from 692 ppm (initial M1) to 546 ppm (heat-treated M2), confirming the effect of annealing on defect reduction.
- Thin Film Analysis: Spectrophotometry (UV-Vis) proved the most effective method for analyzing thin polycrystalline CVD films, allowing the determination of very low nitrogen defect concentrations (C-centers less than 2x1017 atoms/cm3).
- Polycrystalline Quality Assessment: Investigation of coarse-crystalline DSPC (HPHT) and CDM (CVD) diamonds confirmed that their crystallites consist of a highly defective diamond phase, with volumetric diamond content exceeding 99% for CDM and 80% for DSPC.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| CVD Polycrystalline Thickness | 1 - 10 | ”m | Typical deposition rate range |
| Natural Diamond Heat Treatment Temp | 1500 | °C | Vacuum environment, 15 min duration |
| Initial Nitrogen Concentration (M1) | 692 | ppm | Natural single-crystal (Group 26b) |
| Post-HT Nitrogen Concentration (M2) | 546 | ppm | Natural single-crystal (Group 26b) |
| Initial Raman Half-Width (M1) | 10.5 | cm-1 | Indicator of structural imperfection/stress |
| Post-HT Raman Half-Width (M2) | 7.5 | cm-1 | Indicator of structural perfection increase |
| DSPC Synthesis Pressure | 8.0 | GPa | HPHT process parameter |
| DSPC Synthesis Temperature | 1900 | K | HPHT process parameter |
| CDM Diamond Content | >99 | % | Volumetric content (Raman analysis) |
| DSPC Diamond Content | >80 | % | Volumetric content (Raman analysis) |
| C-Center Defect Detection Limit | < 2x1017 | atoms/cm3 | Determined via 272 nm absorption (Spectrophotometry) |
| B-Center IR Absorption Lines | 1363.10, 1180.44 | cm-1 | Characteristic absorption frequencies |
Key Methodologies
Section titled âKey MethodologiesâThe study employed a multi-method spectroscopic approach to characterize four distinct diamond material types:
- Sample Selection: Four material types were analyzed: Polycrystalline CVD films, Natural single-crystal diamonds (M1/M2), Synthetic HPHT DSPC diamonds (8.0 GPa, 1900 K, Ni catalyst), and Polycrystalline CVD CDM diamonds (E6).
- Heat Treatment Protocol: Natural diamond sample M1 was subjected to heat treatment (M2) at 1500 °C in a vacuum for 15 minutes to assess the resulting changes in crystal structure and defect concentration.
- Infrared (IR) Spectrometry:
- Purpose: Determine the total concentration and specific form (e.g., A, B, C centers) of nitrogen inclusions.
- Equipment: Nicolet Thermo IR-spectrometer.
- Application: Used to calculate the reduction in nitrogen concentration post-heat treatment (M1 vs. M2).
- Raman Spectroscopy:
- Purpose: Assess the degree of structural perfection, internal stress, and volumetric content of the diamond phase.
- Equipment: Renishaw inVia and Thermo DXR Raman microscopes.
- Application: Used to measure the narrowing of the diamond line (e.g., 10.5 cm-1 to 7.5 cm-1) as an indicator of reduced stress after annealing.
- Spectrophotometry (UV-Vis):
- Purpose: Most effective method for analyzing thin CVD films where IR/Raman signals are complicated by strong interference. Used to detect small numbers of nitrogen defects.
- Equipment: Cary 400 UV-Vis Spectrophotometer.
- Application: Used to confirm the high quality of CVD films by detecting C-center defects (single nitrogen atoms) at 272 nm.
Commercial Applications
Section titled âCommercial ApplicationsâThe findings and validated analytical techniques are directly relevant to industries requiring precise control over diamond material properties:
- Advanced Thermal Management: The ability to quantify structural perfection (Raman half-width) is crucial for selecting and optimizing CVD diamond substrates used in high-power electronic devices (e.g., GaN/SiC RF components) where thermal conductivity is paramount.
- Optical Components: High-quality, thin polycrystalline CVD films (analyzed via spectrophotometry) are essential for robust optical windows, lenses, and protective coatings requiring minimal absorption and scattering.
- Quantum Sensing and Computing: The precise determination of nitrogen defect types (A, B, C centers) and concentration via IR and UV-Vis spectroscopy is necessary for engineering diamond materials with controlled concentrations of Nitrogen-Vacancy (NV) centers for quantum applications.
- Industrial Tooling and Abrasives: Analysis of HPHT DSPC and CVD CDM materials provides quality assurance regarding the volumetric diamond content and defect density, ensuring performance and longevity in cutting, grinding, and drilling applications.
- Material Certification and Quality Control: The established complex of simple, reliable, and non-destructive spectroscopic methods can be implemented as a standard industrial protocol for rapid quality assessment and classification of diverse diamond substrates.
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.