Decoration of growth sector boundaries with nitrogen vacancy centers in as-grown single crystal high-pressure high-temperature synthetic diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-09-30 |
| Journal | Physical Review Materials |
| Authors | P.L. Diggle, U.F.S. DâHaenens-Johansson, B.L. Green, C.M. Welbourn, Thu Nhi Tran Thi |
| Institutions | Engineering and Physical Sciences Research Council, Gemological Institute of America |
| Citations | 11 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study investigates point defect incorporation in ultra-high purity, low-strain High Pressure High Temperature (HPHT) synthetic diamond, focusing on growth sector boundaries.
- Ultra-High Purity Achieved: The {001} growth sector exhibits exceptional purity, containing less than 1 ppb of substitutional boron and a bulk luminescent defect concentration below 1011 cm-3 (10-3 ppb).
- Low Strain/Dislocations: The material shows low internal strain, with an average dislocation density below 103 cm-2, making it suitable for quantum applications.
- NV- Decoration: Negatively charged Nitrogen Vacancy (NV-) centers are found exclusively decorating the boundaries between the {111} and {113} growth sectors, but not in the bulk sectors themselves.
- Growth Rate Determination: This NV- decoration pattern allows for the calculation of relative growth rates, yielding V113/V111 â 1.13, suggesting stable growth conditions over time.
- Defect Orientation: The NV- and Silicon Vacancy (SiV-) defects show no preferential orientation, consistent with the rapid thermal reorientation of NV- at typical HPHT growth temperatures (< 1 minute at 1500 °C).
- Preferential Nickel Orientation: A nickel-related defect (1.40 eV, 884 nm ZPL) found in the bulk {111} sectors is strongly preferentially oriented, aligning its trigonal axis with the <111> growth direction.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Sample Size | 4.0 x 4.0 x 0.5 | mm | Plate dimensions |
| Average Substitutional Nitrogen [N0] | 6.5 ± 1 | ppb | Measured by EPR (bulk average) |
| Boron [B] Concentration ({001} sector) | < 1 | ppb | Lowest impurity sector |
| Boron [B] Concentration ({111} sector) | 84 ± 10 | ppb | Highest impurity sector |
| Luminescent Defect Concentration ({001}) | < 1011 | cm-3 | Detection limit for common defects |
| Dislocation Density (Average) | < 103 | cm-2 | Overall material quality |
| NV- Single Defect Resolution Limit | 1.76 x 1011 | cm-3 | Bulk concentration equivalent |
| Nickel Defect ZPL | 884 | nm | Zero Phonon Line (1.40 eV defect) |
| Relative Growth Rate (V113/V111) | â 1.13 | N/A | Calculated from decorated boundary angle |
| NV Reorientation Activation Energy (Ea) | â 4.0 | eV | Thermal stability model |
| NV Reorientation Time (at 1500 °C) | < 1 | minute | Time required to lose preferential alignment |
| Excitation Wavelengths (PL) | 488, 532 | nm | Confocal Photoluminescence |
| Cathodoluminescence Temperature | 77 | K | Low temperature measurement |
Key Methodologies
Section titled âKey MethodologiesâThe HPHT diamond was synthesized and characterized using advanced techniques to map defect incorporation and orientation:
-
HPHT Synthesis:
- Method: Temperature gradient method in the diamond thermodynamic stability region.
- Solvent/Catalyst: Co-Fe-C system.
- Purity Control: Proprietary nitrogen getter used to minimize nitrogen incorporation, resulting in Type IIa material.
- Growth Conditions (Typical): 1350 - 1600 °C, with linear growth rates around 50 ”m/hour.
-
Structural and Impurity Assessment:
- X-ray Diffraction (Laue): Confirmed the (001) orientation of the sample plate.
- X-ray Topography (XRT): Used white beam XRT (400 reflection) to visualize extended defects (stacking faults) and confirm low dislocation density.
- Electron Paramagnetic Resonance (EPR): Measured the bulk average concentration of neutral substitutional nitrogen [N0].
- Low Temperature Cathodoluminescence (CL) (77 K): Used the ratio of the boron bound exciton (BE) signal to the free exciton (FE) signal to determine sector-dependent substitutional boron concentrations (detection limit < 1 ppb).
-
Point Defect Mapping and Spectroscopy:
- Confocal Photoluminescence (PL) Microscopy: Diffraction-limited scanning used with 488 nm and 532 nm excitation to map the spatial distribution of NV-, SiV-, and 1.40 eV defects across growth sectors and boundaries.
- Second Order Photon Autocorrelation (g2): Quantified the number of defects in the optical volume to distinguish between single NV- centers and defect ensembles.
- Optically Detected Magnetic Resonance (ODMR): Applied an external magnetic field to measure the spin states and confirm the lack of preferential orientation for NV- centers.
- Optical Polarisation Measurements: Rotated the linear excitation polarization to assess the preferential alignment of SiV- and the 1.40 eV nickel defect based on fluorescence intensity modulation.
Commercial Applications
Section titled âCommercial ApplicationsâThe synthesis of ultra-high purity, low-strain HPHT diamond with controlled defect incorporation is highly relevant to several advanced technological fields:
- Quantum Technologies (Quantum Sensing and Computing):
- The {001} sectorâs high purity and low dislocation density provide an ideal environment for creating high-coherence NV centers (via post-growth methods like ion implantation), crucial for room-temperature quantum sensors (magnetic fields, temperature, pressure).
- The low background impurity concentration minimizes spin decoherence, potentially allowing this HPHT material to outperform âquantum gradeâ CVD diamond in certain applications.
- High-Power Optics and Radiation Windows:
- The large size (> 100 mm3) and low birefringence (due to low strain) make this material suitable for high-energy laser optics and radiation detector windows.
- Fundamental Defect Engineering:
- The clear decoration of growth sector boundaries with NV- centers offers a tool for monitoring and optimizing HPHT growth kinetics and impurity uptake mechanisms in real-time.
- Silicon Vacancy (SiV-) Applications:
- SiV- centers, observed in the {111} sectors, are promising quantum emitters, particularly for integrated photonic circuits, though further work is needed to control their orientation in HPHT growth.
View Original Abstract
Large (> 100 mm$^3$), relatively pure (type II) and low birefringence single\ncrystal diamond can be produced by high pressure high temperature (HPHT)\nsynthesis. In this study we examine a HPHT sample of good crystalline\nperfection, containing less than 1 ppb (part per billion carbon atoms) of boron\nimpurity atoms in the {001} growth sector and only tens of ppb of nitrogen\nimpurity atoms. It is shown that the boundaries between {111} and {113} growth\nsectors are decorated by negatively charged nitrogen vacancy centres (NV$^-$):\nno decoration is observed at any other type of growth sector interface. This\ndecoration can be used to calculated the relative {111} and {113} growth rates.\nThe bulk (001) sector contains concentrations of luminescent point defects\n(excited with 488 and 532 nm wavelengths) below 10$^{11}$ cm$^{-3}$ (10$^{-3}$\nppb). We observe the negatively charged silicon-vacancy (SiV$^-$) defect in the\nbulk {111} sectors along with a zero phonon line emission associated with a\nnickel defect at 884 nm (1.40 eV). No preferential orientation is seen for\neither NV$^-$ or SiV$^-$ defects, but the nickel related defect is oriented\nwith its trigonal axis along the <111> sector growth direction. Since the\nNV$^-$ defect is expected to readily re-orientate at HPHT diamond growth\ntemperatures, no preferential orientation is expected for this defect but the\nlack of preferential orientation of SiV$^-$ in {111} sectors is not explained.\n
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2015 - Handbook of Crystal Growth
- 2015 - Components Packaging Laser System