Generation of Tin-Vacancy Centers in Diamond via Shallow Ion Implantation and Subsequent Diamond Overgrowth
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-02-07 |
| Journal | Nano Letters |
| Authors | Alison E. Rugar, Haiyu Lu, Constantin Dory, Shuo Sun, Patrick J. McQuade |
| Institutions | Stanford University, SLAC National Accelerator Laboratory |
| Citations | 69 |
| Analysis | Full AI Review Included |
Technical Documentation: Generation of High-Quality Tin-Vacancy Centers via SIIG Diamond Overgrowth
Section titled âTechnical Documentation: Generation of High-Quality Tin-Vacancy Centers via SIIG Diamond OvergrowthâThis documentation analyzes the research demonstrating the Shallow Ion Implantation and Growth (SIIG) method for generating high-quality, site-controlled Tin-Vacancy (SnV-) color centers in diamond, a critical advancement for solid-state quantum computing and nanophotonics.
Executive Summary
Section titled âExecutive Summaryâ- Novel Method: Introduction of the Shallow Ion Implantation and Growth (SIIG) technique, which combines low-energy ion implantation with subsequent MPCVD diamond overgrowth.
- Quality Achievement: SIIG successfully generated SnV- centers exhibiting clean bulk Photoluminescence (PL) spectra, notably suppressing extraneous emission peaks (631 nm and 647 nm) typically associated with lattice damage.
- HPHT Avoidance: The high-quality results achieved via SIIG were previously only possible using complex High-Pressure High-Temperature (HPHT) annealing, making SIIG a simpler, more scalable alternative.
- Site Control: The use of low-energy implantation (1 keV) allowed for precise, site-controlled generation using a simple, thin PMMA mask (~50 nm), compatible with existing nanophotonic fabrication techniques.
- Lattice Healing: The MPCVD overgrowth layer (90 nm) effectively healed lattice damage and incorporated the implanted Sn atoms into the growing diamond lattice, forming low-strain SnV- centers.
- Narrow Broadening: Optimized SIIG preparation (Sample C) achieved extremely narrow inhomogeneous broadening (as low as 101 ± 1 GHz), demonstrating high crystal quality around the emitters, suitable for techniques like Raman tuning.
- Versatility: The method utilizes standard MPCVD growth conditions for pure diamond, suggesting high compatibility and potential extension to other Group-IV color centers (e.g., GeV, PbV).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the SIIG methodology (Sample B and optimized Sample C):
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Substrate Material | Electronic Grade Diamond | N/A | Starting material (Single Crystal Diamond) |
| Initial Etch Depth | 500 | nm | Removed via O2 plasma etch |
| Implantation Species | 120Sn+ | N/A | Tin isotope used for color center creation |
| Implantation Energy (SIIG) | 1 | keV | Low-energy implantation for shallow localization |
| Implantation Dose | 2 x 1013 | cm-2 | Standard dose used for both methods |
| Mask Thickness (PMMA) | ~ 50 | nm | Thin mask used for site control |
| MPCVD Overgrowth Thickness | 90 | nm | Layer grown immediately after implantation |
| MPCVD Stage Temperature | 650 | °C | Growth temperature for lattice healing |
| MPCVD Microwave Power | 1100 | W | Power setting (Seki Diamond Systems SDS 5010) |
| MPCVD Pressure | 23 | Torr | Growth pressure |
| Inhomogeneous Broadening (C-transition, Sample C) | 101 ± 1 | GHz | Full Width at Half-Maximum (FWHM) at 5 K |
| Inhomogeneous Broadening (D-transition, Sample C) | 105 ± 2 | GHz | Full Width at Half-Maximum (FWHM) at 5 K |
| Sn Ion Localization Depth | ~ 2 | nm | Calculated depth of ions near surface |
Key Methodologies
Section titled âKey MethodologiesâThe Shallow Ion Implantation and Growth (SIIG) method involves the following critical steps for Sample B:
- Substrate Cleaning: Electronic grade diamond plates were subjected to a boiling tri-acid clean (1:1:1 sulfuric:nitric:perchloric acids).
- Surface Etch: A 500 nm layer of diamond was removed using an O2 plasma etch to ensure a clean starting surface.
- Mask Application: A thin layer (~50 nm) of poly(methyl methacrylate) (PMMA) was spin-coated onto the substrate.
- Patterning: The PMMA mask was patterned using electron-beam (e-beam) lithography to define arrays of holes (20 nm to 150 nm) for site-controlled implantation.
- Shallow Implantation: 120Sn+ ions were implanted at a low energy of 1 keV with a dose of 2 x 1013 cm-2.
- Mask Removal: The PMMA mask was chemically removed (Remover PG).
- Plasma Clean: The surface was cleaned using H2 plasma to remove sp2-bonded carbon resulting from implantation damage.
- MPCVD Overgrowth: A 90 nm thick diamond layer was grown immediately via MPCVD using the following recipe:
- Stage Temperature: 650 °C
- Microwave Power: 1100 W
- Pressure: 23 Torr
- Gas Flows: 300 sccm H2; 0.5 sccm CH4
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful implementation of the SIIG method relies entirely on high-quality diamond substrates and precision MPCVD growth capabilitiesâ6CCVDâs core expertise. We offer materials and services specifically tailored to replicate and advance this quantum research.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, a high-purity, low-defect starting material is essential to minimize background noise and achieve the narrow inhomogeneous broadening demonstrated in the paper.
- Recommendation: Optical Grade Single Crystal Diamond (SCD).
- Our SCD wafers provide the ultra-low nitrogen and defect density required for quantum applications.
- We offer SCD in thicknesses ranging from 0.1”m up to 500”m, suitable for initial etching and subsequent overgrowth.
Customization Potential
Section titled âCustomization PotentialâThe SIIG method critically depends on the quality and control of the CVD overgrowth layer to heal lattice damage and precisely position the $\delta$-doped layer of SnV- centers.
- Precision Epitaxial Growth: 6CCVD specializes in Custom MPCVD Epitaxial Growth Services. We can precisely control the thickness of the overgrowth layer (e.g., 90 nm, as used in the study) and tailor growth parameters (temperature, pressure, gas ratios) to optimize defect incorporation and lattice healing, ensuring the low-strain environment necessary for high-quality SnV- centers.
- Custom Dimensions and Shaping: We offer advanced laser cutting and shaping services to produce chips, plates, or wafers up to 125mm (PCD) or custom SCD dimensions, ready for e-beam lithography and subsequent nanophotonic device fabrication (e.g., nanocavities, nanobeams).
- Metalization for Device Integration: For researchers integrating these color centers into functional nanophotonic devices, 6CCVD provides In-House Metalization Services (Au, Pt, Pd, Ti, W, Cu) to deposit contacts directly onto the diamond surface.
Engineering Support
Section titled âEngineering SupportâThe optimization of the SIIG process (as seen in the contrast between Sample B and Sample C) highlights the importance of expert material preparation and recipe tuning.
- Expert Consultation: 6CCVDâs in-house PhD team can assist with material selection and process optimization for similar Group-IV Color Center Generation projects (SnV-, GeV-, PbV-). We provide authoritative guidance on achieving optimal substrate quality, etch depths, and growth recipes to minimize inhomogeneous broadening and maximize emitter quality.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Group IV color centers in diamond have garnered great interest for their potential as optically active solid-state spin qubits. The future utilization of such emitters requires the development of precise site-controlled emitter generation techniques that are compatible with high-quality nanophotonic devices. This task is more challenging for color centers with large group IV impurity atoms, which are otherwise promising because of their predicted long spin coherence times without a dilution refrigerator. For example, when applied to the negatively charged tin-vacancy (SnV<sup>-</sup>) center, conventional site-controlled color center generation methods either damage the diamond surface or yield bulk spectra with unexplained features. Here we demonstrate a novel method to generate site-controlled SnV<sup>-</sup> centers with clean bulk spectra. We shallowly implant Sn ions through a thin implantation mask and subsequently grow a layer of diamond via chemical vapor deposition. This method can be extended to other color centers and integrated with quantum nanophotonic device fabrication.