Generation of shallow nitrogen-vacancy centers in diamond with carbon ion implantation
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | Acta Physica Sinica |
| Authors | Jian He, Yanwei Jia, Ju-Ping Tu, Tian Xia, Xiaohua Zhu |
| Institutions | University of Science and Technology Beijing |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Generation of Shallow Nitrogen-Vacancy Centers in Diamond via Carbon Ion Implantation
Section titled âTechnical Documentation & Analysis: Generation of Shallow Nitrogen-Vacancy Centers in Diamond via Carbon Ion ImplantationâThis document analyzes the research paper âGeneration of shallow nitrogen-vacancy centers in diamond with carbon ion implantationâ (Acta Phys. Sin. Vol. 71, No. 18, 2022) and outlines how 6CCVDâs advanced MPCVD diamond materials and processing capabilities can support and extend this critical quantum research.
Executive Summary
Section titled âExecutive SummaryâThe research successfully demonstrates a method for creating shallow Nitrogen-Vacancy (NV) centers in diamond using low-energy Carbon (C) ion implantation followed by high-temperature vacuum annealing. This approach is highly relevant for quantum sensing applications requiring surface-proximal defects.
- Core Achievement: Successful formation of shallow NV centers ([N-V]0 at 575 nm and [N-V]- at 637 nm) in Type Ib diamond using 180 keV C-ion implantation and 950 °C vacuum annealing.
- Mechanism Elucidation: The study confirms that C-ion implantation creates carbon-vacancy cluster defects; subsequent 950 °C annealing drives solid-phase epitaxy, recovering the damaged layer, and promoting cluster dissociation, allowing native substitutional nitrogen (Ns) to capture the released single vacancies.
- Material Recovery: XPS analysis showed significant recovery of the implantation-induced amorphous carbon layer (sp2 content dropped from 91.5% post-implant to 13.6% after 950 °C annealing).
- Advantages: The C-ion method avoids introducing new impurity atoms and requires lower initial diamond purity compared to traditional N-ion implantation, making it cost-effective and versatile.
- Target Depth: SRIM simulation confirmed the peak damage (vacancy density) occurred at a shallow depth of 215 nm, ideal for high-sensitivity quantum sensors.
- 6CCVD Relevance: 6CCVD specializes in MPCVD SCD with precise nitrogen control and superior surface quality (Ra < 1 nm), offering ideal starting materials for replicating and optimizing this shallow NV center fabrication technique.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental methodology and results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Base Material Type | Type Ib HPHT SCD | - | Commercial, double-sided polished |
| Initial Nitrogen Concentration | ~100 x 106 | ppm | Calculated via IR absorption (1130 cm-1) |
| Ion Species | Carbon (C+) | - | Implantation Source |
| Ion Energy | 180 | keV | Low-energy implantation |
| Ion Dose | 5 x 1016 | C+/cm2 | High dose used to maximize vacancy creation |
| Implantation Angle | Perpendicular | - | - |
| Annealing Temperatures (TA) | 850, 900, 950 | °C | Vacuum Annealing Conditions (S1, S2, S3) |
| Annealing Time | 2 | hours | - |
| Simulated Peak Damage Depth | 215 | nm | SRIM simulation result |
| Simulated Maximum Ion Range | 284 | nm | SRIM simulation result |
| Post-Implant sp2 Content | 91.5 | % | XPS analysis of damaged surface layer |
| Post-950 °C Anneal sp2 Content | 13.6 | % | Indicates significant lattice recovery |
| NV Center Emission (Neutral) | 575 | nm | Photoluminescence (PL) for [N-V]0 |
| NV Center Emission (Negative) | 637 | nm | Photoluminescence (PL) for [N-V]- |
Key Methodologies
Section titled âKey MethodologiesâThe experiment focused on creating and characterizing shallow NV centers using controlled C-ion implantation and subsequent thermal processing.
- Material Selection and Cleaning: Commercial Type Ib HPHT single crystal diamond was used. Samples were polished and then cleaned in a 300 °C acid mixture (HNO3:H2SO4, 1:4) to remove surface graphite and metallic contaminants.
- Carbon Ion Implantation: Performed using a 400 keV ion implanter. The specific parameters were 180 keV energy, 5 x 1016 C+/cm2 dose, and perpendicular incidence to the diamond surface.
- Vacuum Annealing: Samples were subjected to vacuum annealing for 2 hours at three distinct temperatures: 850 °C (S1), 900 °C (S2), and 950 °C (S3).
- Structural and Defect Characterization:
- Raman and PL Spectroscopy: Used to analyze lattice defects (D and G peaks) and confirm the presence of NV centers (575 nm and 637 nm peaks).
- X-ray Photoelectron Spectroscopy (XPS): Used to quantify the ratio of sp2 (amorphous carbon) to sp3 (diamond) bonding, tracking the recovery of the damaged layer during annealing.
- Positron Annihilation Spectroscopy (PAS): Employed a variable-energy slow positron beam to analyze vacancy-type defects and their depth distribution (S-E and W-E curves), confirming the presence of carbon-vacancy clusters.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the high-quality MPCVD diamond materials and precision processing required to replicate, optimize, and scale the production of shallow NV centers for advanced quantum applications.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, 6CCVD recommends the following MPCVD diamond materials, offering superior purity and control compared to the HPHT material used in the study:
| 6CCVD Material Recommendation | Description & Relevance to Research |
|---|---|
| High-Nitrogen SCD (Type Ib Equivalent) | MPCVD Single Crystal Diamond grown with controlled nitrogen doping (Ns concentration up to 100 ppm or higher). This material directly supports the mechanism studied, providing the necessary substitutional nitrogen source for NV formation. |
| Ultra-Low Nitrogen SCD (Type IIa) | SCD with N concentration typically < 1 ppm. Ideal for studies where nitrogen is introduced externally (e.g., N-ion implantation) or for creating NV centers only in specific, localized regions, ensuring minimal background noise. |
| Optical Grade SCD Wafers | Essential for quantum sensing applications. Our SCD is optimized for low birefringence and high transmission at the 532 nm excitation and NV emission wavelengths (575/637 nm). |
Customization Potential
Section titled âCustomization PotentialâThe success of shallow NV creation relies heavily on the quality of the starting material and precise post-processing. 6CCVD offers comprehensive customization services:
| Research Requirement | 6CCVD Customization Service |
|---|---|
| Surface Quality: Need for ultra-low surface defects to maintain NV coherence (T2). | Precision Polishing: We provide SCD polishing to Ra < 1 nm and inch-size PCD polishing to Ra < 5 nm, minimizing surface roughness that degrades shallow NV performance. |
| Dimensions: Need for specific sample sizes compatible with ion implanters and vacuum furnaces. | Custom Dimensions & Shaping: We supply plates and wafers up to 125 mm (PCD) and offer precision laser cutting and shaping services to meet exact experimental geometry requirements. |
| Shallow Layer Study: Need for thin, high-quality material for depth-resolved analysis. | Thickness Control: SCD and PCD wafers are available in thicknesses ranging from 0.1 ”m to 500 ”m, allowing researchers to precisely match material thickness to the required implantation depth (e.g., 215 nm damage peak). |
| Device Integration: Need for electrical or microwave contacts for ODMR/sensing devices. | Custom Metalization: We offer internal deposition of standard metal stacks (Au, Pt, Pd, Ti, W, Cu) for creating ohmic contacts or microwave striplines directly onto the diamond surface post-annealing. |
Engineering Support
Section titled âEngineering SupportâThe complex interplay between ion energy, dose, annealing temperature, and initial nitrogen concentration requires expert material consultation.
6CCVDâs in-house PhD team can assist researchers with material selection and specification for similar shallow quantum sensing and magnetic detection projects. We provide guidance on optimizing nitrogen concentration in the SCD growth phase to maximize the yield and coherence time (T2) of the resulting NV centers.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The shallow nitrogen-vacancy center of diamond exhibits excellent sensitivity and resolution in the magnetic detection and quantum sensing areas. Compared with other methods, low-energy carbon ion implantation does not need high-purity diamond nor introduce new impurity atoms, but the formation mechanism of nitrogen-vacancy center is not clear. In this work, shallow nitrogen-vacancy centers are created in the diamond by low energy carbon ion implantation and vacuum annealing, and the transformation mechanism of nitrogen-vacancy centers in diamond is studied by Raman spectroscopy, X-ray photoelectron spectroscopy, and positron annihilation analysis. The results show that shallow nitrogen-vacancy centers can be obtained by carbon ion implantation combined with vacuum annealing. After implantation, superficial layer of diamond shows the damage zone including lattice distortion and amorphous carbon, and carbon-vacancy cluster defects (carbon atoms are surrounded by vacancy clusters) are generated. In the vacuum annealing process, the damaged area gradually transforms into the diamond structure through the recovery of the distortion area and the solid-phase epitaxy of the amorphous carbon area, accompanied by the continuous dissociation of carbon-vacancy cluster defects. When samples are annealed at 850 and 900 â, the structure of the damaged area is partially repaired. While annealing at 950 â, not only the damaged layer is basically recovered, but also nitrogen atoms capture the single vacancy obtained by the dissociation of carbon vacancy clusters, forming the nitrogen-vacancy centers.