Efficient Generation of an Array of Single Silicon-Vacancy Defects in Silicon Carbide
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-06-16 |
| Journal | Physical Review Applied |
| Authors | Junfeng Wang, Yu Zhou, Xiaoming Zhang, Fucai Liu, Yan Li |
| Institutions | Hefei National Center for Physical Sciences at Nanoscale, University of Science and Technology of China |
| Citations | 100 |
| Analysis | Full AI Review Included |
High-Efficiency Generation of Quantum Defect Arrays: An Analysis for Quantum Engineering Substrates
Section titled âHigh-Efficiency Generation of Quantum Defect Arrays: An Analysis for Quantum Engineering Substratesâ6CCVD analyzes the feasibility and extension of creating highly efficient, position-controlled quantum defect arrays demonstrated in silicon carbide (SiC) to the superior performance platforms offered by Single Crystal Diamond (SCD) substrates.
Executive Summary
Section titled âExecutive Summaryâ- Core Achievement: Demonstration of high-efficiency generation (41%) of nanoscale single Silicon Vacancy (VSi) defect arrays in 4H-SiC using 30 keV Carbon ion implantation through Electron Beam Lithography (EBL) patterned masks.
- Precision and Integration: The method achieved defect localization accuracy in the tens of nanometers, essential for precise integration with advanced photonic structures like Solid Immersion Lenses (SILs) and photonic crystal cavities.
- High Yield: A high conversion yield of implanted carbon ions into VSi defects (~19%) was achieved without the need for post-implantation annealing, simplifying the fabrication procedure.
- Quantum Relevance: The VSi centers exhibit stable single-photon emission, high photostability (no photo-blinking over 60s), and long spin coherence times (up to 160 ”s), confirming their suitability as spin qubits and quantum sensors.
- Diamond Parallels: This targeted defect creation technique is directly applicable to generating Nitrogen Vacancy (NV) centers in diamond, offering a pathway to scalable, high-coherence diamond quantum devices.
- 6CCVD Value Proposition: 6CCVD specializes in Electronic Grade Single Crystal Diamond (SCD) with ultra-low nitrogen content, providing the ideal foundation for maximizing the coherence and purity of engineered quantum defects like NV centers for next-generation quantum applications.
Technical Specifications
Section titled âTechnical SpecificationsâThe following parameters were extracted from the experimental methodology and characterization results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Defect Material | 4H-SiC | N/A | High-purity epitaxy layer sample |
| Target Defect | Single Silicon Vacancy (VSi) | N/A | Used for spin qubits/sensing |
| Implantation Species | C+ (Carbon Ion) | N/A | Used to generate VSi |
| Implantation Energy | 30 | keV | |
| Implantation Fluence | 2.6 x 1011 | C+/cm2 | Used through PMMA mask |
| Aperture Diameter | 65 ± 10 | nm | PMMA mask resolution (EBL patterned) |
| Array Cell Separation | 2 | ”m | Center-to-center pitch |
| Average Defect Depth | ~42 | nm | Simulated by SRIM |
| Defect Longitudinal Straggling | ~35 | nm | Positional accuracy limitation |
| Single VSi Generation Efficiency | 41 | % | Percentage of implanted sites yielding a single VSi |
| Conversion Yield | 19 | % | Implanted C ions converted into VSi defects |
| Room Temperature PL Count (Saturation) | 7.4 | kcps | Single VSi maximum count rate |
| Excitation Wavelength | 690 | nm | Continuous Wave (CW) laser |
| Measurement Temperature (ODMR) | 5 | K | Used for highly-resolved PL and ODMR |
| V2 Center Resonant Frequency | 68.4 | MHz | Zero-field ODMR measurement |
Key Methodologies
Section titled âKey MethodologiesâThe VSi defect array was efficiently generated in a top-down fabrication sequence:
- Substrate Preparation: High-purity 4H-SiC epitaxy layer cleaned via ultrasonication in acetone and isopropanol (IPA).
- Mask Deposition: A 300 nm thick PMMA layer (A7:A4 = 5:3) was deposited via spin-coating onto the SiC surface.
- Patterning: Electron Beam Lithography (EBL) was used to pattern an array of 65 nm diameter apertures with 2 ”m cell separation.
- Ion Implantation: 30 keV C+ ions were implanted through the PMMA mask at a fluence of 2.6 x 1011 C+/cm2. SRIM simulation confirmed the 300 nm mask blocked >99% of the ions outside the apertures.
- Mask Removal: The PMMA layer was removed by ultrasonication in acetone and subsequently cleaned in IPA. No post-implantation thermal annealing was used.
- Characterization: Defects were analyzed using room-temperature photoluminescence (PL), HBT second-order correlation function g2(t) to confirm single-emitter status, and low-temperature (5 K) optically detected magnetic resonance (ODMR).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful nanoscale positioning and high-efficiency generation of defects in SiC directly demonstrates methodologies critical for quantum engineering in diamond (NV centers, SiV, GeV, etc.). 6CCVD offers specialized MPCVD diamond substrates and processing services necessary to replicate and advance this research using materials optimized for superior quantum performance.
Applicable Materials
Section titled âApplicable Materialsâ| Research Requirement | 6CCVD Material Recommendation | Material Advantage |
|---|---|---|
| Quantum Defect Generation (Spin Qubits) | Electronic Grade Single Crystal Diamond (SCD) | Ultra-low N content (N < 5 ppb) ensures minimal background noise and maximum coherence time, essential for high-fidelity qubits analogous to high-purity 4H-SiC. |
| Nanoscale Sensing & Shallow Defects | High-Purity SCD (0.1”m - 5”m thickness) | Provides an atomically stable host matrix for creating ultra-shallow defects (analogous to the 42 nm depth VSi defects) vital for nanoscale magnetometry near the surface. |
| Scalable Arrays & Engineering | Large-Area Polycrystalline Diamond (PCD) | Available in plates up to 125 mm diameter, offering a scalable, cost-effective platform for sensing applications that require wide-area defect arrays, surpassing typical SCD wafer size limits. |
| High Thermal Management | SCD or PCD Substrates | Diamond possesses the highest thermal conductivity (2000 W/mK) of any material, critical for managing heat during high-power optical excitation in room-temperature quantum devices. |
Customization Potential
Section titled âCustomization PotentialâThe methodology required precise thin-film masks (PMMA) and microwave control structures (20 ”m strip lines). 6CCVD offers end-to-end material customization to support these requirements:
- Ultra-Smooth Substrates: SCD polishing to Ra < 1 nm is available, ensuring optimal surface quality for subsequent lithography steps (EBL or optical resist patterning) necessary for achieving the reported 65 nm resolution.
- Custom Dimensions: 6CCVD provides precision laser cutting and dicing services for SCD and PCD wafers (up to 125 mm) to create custom sample sizes or specialized geometries required for mounting within cryostats or confocal microscopy setups.
- Metalization Services: We offer internal capability for deposition of contact and transmission lines (e.g., Ti/Au, Pt) directly onto the diamond surface. This capability is crucial for fabricating the 20 ”m wide microwave strip lines used for ODMR control in quantum sensing experiments.
- Thick Substrates for Optics: We supply SCD substrates up to 500 ”m thick and backing substrates up to 10 mm thick, supporting the robust fabrication of on-chip optical elements like Solid Immersion Lenses (SILs) or nano-pillar structures mentioned as next steps in the paper.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house team of PhD material scientists and CVD engineers can assist researchers and engineers in selecting the optimal diamond substrate specifications (purity, orientation, polish, and custom thickness) for projects involving quantum sensing, spin qubits, and integrated spin photonics networks, ensuring compatibility with advanced defect creation techniques like ion implantation and etching.
Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Color centers in silicon carbide have increasingly attracted attention in recent years owing to their excellent properties such as single-photon emission, good photostability, and long spin-coherence time even at room temperature. As compared to diamond, which is widely used for hosting nitrogen-vacancy centers, silicon carbide has an advantage in terms of large-scale, high-quality, and low-cost growth, as well as an advanced fabrication technique in optoelectronics, leading to prospects for large-scale quantum engineering. In this paper, we report an experimental demonstration of the generation of a single-photon-emitter array through ion implantation. VSi defects are generated in predetermined locations with high generation efficiency (approximately 19%±4%). The single emitter probability reaches approximately 34%±4% when the ion-implantation dose is properly set. This method serves as a critical step in integrating single VSi defect emitters with photonic structures, which, in turn, can improve the emission and collection efficiency of VSi defects when they are used in a spin photonic quantum network. On the other hand, the defects are shallow, and they are generated about 40 nm below the surface which can serve as a critical resource in quantum-sensing applications.