Determination of local defect density in diamond by double electron-electron resonance
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-09-24 |
| Journal | Physical review. B./Physical review. B |
| Authors | Li Shang, Huijie Zheng, Zaili Peng, Mizuki Kamiya, Tomoyuki Niki |
| Institutions | University of Southern California, GSI Helmholtz Centre for Heavy Ion Research |
| Citations | 21 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Local Defect Density in Diamond via DEER
Section titled âTechnical Documentation & Analysis: Local Defect Density in Diamond via DEERâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the use of Double Electron-Electron Resonance (DEER) coupled with Optically Detected Magnetic Resonance (ODMR) to locally determine the concentration of paramagnetic defects, specifically P1 centers (substitutional nitrogen) and other impurity spins, within single-crystal diamond (SCD).
- Core Achievement: Localized measurement of P1 center concentration ([P1]) ranging from 13 ppm to 322 ppm, revealing significant spatial inhomogeneity in HPHT-grown diamond samples.
- Critical Finding: The high variability and concentration of P1 centers directly impact the NV- center spin relaxation time (T2), which is crucial for quantum sensing and computing applications.
- Methodology: The technique utilizes the NV- center as a probe spin (MW1) and P1 centers as target spins (MW2), allowing for quantitative analysis of defect density without an external reference sample.
- Material Requirement: High-quality SCD is essential, but the observed inhomogeneity in HPHT material necessitates advanced growth control to achieve uniform defect densities required for optimized sensors.
- 6CCVD Value Proposition: 6CCVDâs expertise in MPCVD growth allows for precise, low-ppm control of nitrogen incorporation, enabling the production of highly uniform SCD wafers engineered specifically for optimal NV- ensemble performance and extended T2 coherence times.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper, detailing material properties and experimental parameters:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| P1 Concentration Range | 13 to 322 | ppm | Observed range across S5 sample locations. |
| NV- Concentration | 17 | ppm | Locally determined concentration at spot S5-1. |
| Unknown Defect Concentration [Ex] | 4.1(2) | ppm | Concentration of g~2 spin defect species. |
| Decoherence Time (T2) | 1.22 ± 0.02 | ”s | Measured at spot S5-1. |
| E-beam Energy (S2, S5) | 3 | MeV | Used for NV- creation. |
| E-beam Dose (S2, S5, D12, F32) | 1018 | cm-2 | Standard dose for NV- creation. |
| Annealing Temperature (S2, S5) | 1050 | °C | Annealing condition in forming gas (2 hrs). |
| Annealing Temperature (D12, F32) | 700 | °C | Annealing condition (3 hrs). |
| Static Magnetic Field (B0) | 22.7 | mT | Used for ODMR/DEER measurements. |
| Zero-Field Splitting (D) | 2.87 | GHz | NV- ground state splitting constant. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relied on a multi-step material preparation and a sophisticated optical/microwave setup:
- Sample Preparation: High-Pressure, High-Temperature (HPHT) synthesized SCD plates ([100]-cut and [111]-cut) were used.
- NV- Creation: Samples underwent high-energy electron-beam irradiation (3 MeV to 14 MeV) at a dose of 1018 cm-2 to create vacancies.
- Thermal Annealing: Irradiated samples were annealed at high temperatures (700 °C to 1050 °C) in a forming gas (Ar/H2) to mobilize vacancies and form NV centers.
- ODMR Setup: A conventional confocal ODMR setup was used, employing a 532 nm laser focused to a spot size of approximately 10 ”m. Photoluminescence (PL) was collected via a dichroic mirror and detected by an avalanche photo-detector.
- DEER Pulse Sequence: The core measurement involved a spin-echo sequence (MW1, NV- probe spins) combined with an additional Ï-pulse (MW2, P1 target spins) to induce a shift in the magnetic dipole field, allowing for localized concentration determination.
- Data Analysis: The normalized DEER signal (IDEER) was fitted using theoretical models (Eq. 5) to extract the spin concentration (n) and the ESR linewidth (ÎÏ) of the target P1 centers.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research highlights a critical challenge in diamond quantum materials: the spatial inhomogeneity of defects in HPHT-grown crystals, which limits sensor performance. 6CCVDâs advanced MPCVD growth and processing capabilities are specifically designed to overcome these limitations, providing engineers and scientists with the highly controlled materials necessary to replicate and extend this research.
Applicable Materials for Replication and Extension
Section titled âApplicable Materials for Replication and ExtensionâTo achieve the uniform, low-defect density required for optimal T2 coherence times and high-fidelity quantum experiments, 6CCVD recommends the following materials:
| 6CCVD Material Grade | Description & Application | Relevance to Research |
|---|---|---|
| High Purity SCD (Optical Grade) | SCD with ultra-low native nitrogen concentration (< 1 ppb). Ideal for creating NV centers via controlled ion implantation or low-dose irradiation. | Essential for minimizing background P1 noise and maximizing T2 coherence time, directly addressing the paperâs findings on P1 limits. |
| Engineered SCD (Controlled Doping) | SCD grown with precise, intentional nitrogen incorporation (e.g., 0.5 ppm to 10 ppm) via the gas phase. | Allows for the creation of uniform NV ensembles at specific, desired concentrations, eliminating the spatial inhomogeneity observed in the HPHT samples. |
| Boron-Doped Diamond (BDD) | SCD or PCD doped with Boron. | Relevant for extending the DEER technique to characterize other defect species or for electrochemical sensing applications. |
Customization Potential for Advanced Quantum Devices
Section titled âCustomization Potential for Advanced Quantum DevicesâThe DEER technique requires precise control over the local environment, often involving integrated microwave structures. 6CCVD offers comprehensive customization services to facilitate advanced research:
- Custom Dimensions and Geometry: 6CCVD supplies SCD plates and wafers up to 125mm (PCD) and substrates up to 10mm thick. We can provide custom laser cutting and shaping to fit specific microwave circuit designs (e.g., transmission lines with 200 ”m gaps, as mentioned in the paper).
- Precision Purity Control: Unlike the variable P1 concentrations (13-322 ppm) found in the HPHT samples, 6CCVD guarantees nitrogen concentration control in the ppb to ppm range, ensuring highly uniform NV- ensemble formation.
- Advanced Metalization Services: For integrating the microwave transmission lines (MW1 and MW2) directly onto the diamond surface, 6CCVD offers in-house metalization capabilities, including Au, Pt, Pd, Ti, W, and Cu deposition, tailored to specific microwave impedance requirements.
- Ultra-Low Roughness Polishing: Our SCD polishing achieves surface roughness (Ra) < 1nm, which is critical for minimizing surface noise and enabling high-fidelity nanoscale sensing applications.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the physics and material science of NV centers and spin defects. We can assist researchers in:
- Material Selection: Consulting on the optimal starting material purity and thickness for specific NV creation methods (e.g., implantation vs. in-situ doping).
- Process Optimization: Guiding the selection of E-beam irradiation and annealing recipes to maximize NV yield and minimize unwanted defect species, based on the local defect density analysis demonstrated in this paper.
- Application Extension: Providing material solutions for similar quantum sensing, nanoscale magnetic detection, and quantum computing projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Magnetic impurities in diamond influence the relaxation properties and thus limit the sensitivity of magnetic, electric, strain, and temperature sensors based on nitrogen-vacancy color centers. Diamond samples may exhibit significant spatial variations in the impurity concentrations hindering the quantitative analysis of relaxation pathways. Here, we present a local measurement technique which can be used to determine the concentration of various species of defects by utilizing double electron-electron resonance. This method will help to improve the understanding of the physics underlying spin relaxation and guide the development of diamond samples, as well as offering protocols for optimized sensing.