SINGLE-CRYSTAL DIAMOND NEMS DEVICES FOR THE STUDY OF COLOR CENTERS
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-05-26 |
| Journal | 2016 Solid-State, Actuators, and Microsystems Workshop Technical Digest |
| Authors | Young-Ik Sohn, Srujan Meesala, Michael J. Burek, Haig A. Atikian, Marko LonÄar |
| Institutions | Harvard University |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Single-Crystal Diamond NEMS Devices for Color Centers
Section titled âTechnical Documentation & Analysis: Single-Crystal Diamond NEMS Devices for Color CentersâExecutive Summary
Section titled âExecutive SummaryâThis document analyzes the research demonstrating the fabrication and application of Micro/Nano-Electromechanical Systems (MEMS/NEMS) devices in single-crystal diamond (SCD) for quantum information science (QIST).
- Core Achievement: Successful fabrication of free-standing SCD nanostructures (cantilevers and nanobeams) using a specialized angled-etching technique combined with conventional e-beam lithography and lift-off processes.
- Application Focus: Controlled generation of static and dynamic strain fields to tune the electronic and spin energy levels of embedded solid-state qubits, specifically Silicon Vacancy (SiV) color centers.
- High Performance Metrics: Demonstrated dynamic actuation enabling extremely high mechanical performance, achieving an fQ product (frequency x quality factor) of 6.8 x 1012.
- Actuation Methods: Two complementary methods were utilized: high-Q dynamic actuation via dielectrophoretic force, and high-strain static actuation (up to 150 VDC) via electrostatic force.
- Material Necessity: Success is fundamentally dependent on the use of high-purity, high-quality bulk SCD, which minimizes defects and preserves high mechanical Q-factors.
- 6CCVD Value Proposition: 6CCVD offers the custom-thickness SCD material and precise metalization capabilities required to replicate and advance this cutting-edge quantum sensing technology.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted relating to the material properties, device performance, and process parameters:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Core Material | Single Crystal Diamond | N/A | Substrate utilized for NEMS fabrication. |
| Target Qubit | Silicon Vacancy (SiV) Center | N/A | Electronic levels tuned via applied strain. |
| Thickness (Simulated Cantilever) | 830 | nm | Thickness crucial for electrostatic strain optimization. |
| Width (High Q Cantilever) | 260 | nm | Minimum lateral dimension demonstrated. |
| Resonant Frequency (Cantilever) | 18.3 | MHz | Dielectrophoretic dynamic actuation measurement. |
| Max fQ Product Achieved | 6.8 x 1012 | Hz | Figure of merit for high-performance resonators. |
| Max DC Actuation Voltage | 150 | V | Applied for SiV electronic level tuning (static strain). |
| Maximum Simulated Tip Displacement | 150 | nm | Achieved using 120 VDC on a 30 ”m long cantilever. |
| RIE Oxygen Plasma Power | 100 | W | Used for oxygen plasma clean / vertical etch. |
| RIE Oxygen Plasma Pressure | 250 | mTorr | Used for oxygen plasma clean / vertical etch. |
| Metalization Layer | Gold (Au) | N/A | Used for driving electrodes in both actuation schemes. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment successfully combined specialized plasma etching with standard cleanroom processes to create free-standing SCD structures, a critical challenge given the materialâs bulk synthesis nature.
- Lithography and Masking: E-beam lithography (EBL) used in conjunction with resists (HSQ, PMMA/MMA bi-layer) to define patterns, incorporating alignment markers for high precision.
- Vertical Reactive-Ion Etching (RIE): Initial pattern transfer into the SCD using oxygen plasma chemistry (100 W, 250 mTorr) to establish vertical sidewalls.
- Angled-Etching using Faraday Cage: A Faraday cage was introduced into the RIE chamber to manipulate the plasmaâs electrical potential and sheath, causing ions to accelerate obliquely. This enables the undercut necessary to create free-standing structures with triangular cross-sections.
- Electrode Fabrication (Lift-off): A bi-layer lift-off process was performed, followed by evaporation of metal (Gold, Au) to form the electrostatic or dielectrophoretic actuation electrodes.
- Surface Preservation: Critical point drying (CPD) was employed for small nanobeams to prevent device snapping or adhesion (stiction) to the substrate during the final release step.
- Characterization: Photoluminescence Excitation (PLE) measurements confirmed the application of strain by monitoring shifts in the characteristic emission wavelengths of the embedded SiV center.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the advanced MPCVD diamond materials and precision engineering services required to replicate and extend this foundational work in diamond quantum MEMS/NEMS.
Applicable Materials
Section titled âApplicable MaterialsâThe success of high-Q NEMS devices and qubit experiments relies heavily on the substrateâs purity and surface quality.
| Required Material Property | 6CCVD Solution | Technical Advantage |
|---|---|---|
| High Purity Substrate | Optical Grade Single Crystal Diamond (SCD) | Minimizes intrinsic defects (like nitrogen, N) to guarantee low background color center density, ideal for controlled SiV or NV incorporation. |
| Electrically Actuated Devices | Metalized SCD/PCD | Customization for electrostatic actuation, offering conductive layers with controlled residual stress using Ti/Pt/Au or W stacks to prevent Q degradation or pull-in instability. |
| Controlled Doping (Extension) | Boron-Doped Diamond (BDD) | For future research requiring conductivity or modified optical properties, BDD can be supplied in thin film or bulk formats. |
Customization Potential
Section titled âCustomization PotentialâThe research highlights the critical importance of sub-micrometer dimensional control and precise metal deposition. 6CCVDâs internal capabilities directly address these challenges:
- Custom Dimensions and Thickness: The NEMS devices required precise SCD thicknesses (e.g., 830 nm). 6CCVD offers Single Crystal Diamond (SCD) wafers with specified thickness control ranging from 0.1 ”m up to 500 ”m, crucial for tailoring mechanical resonance frequencies and stiffness ($f$ and $Q$).
- Large-Scale Platform Integration: 6CCVD can provide large-area substrates, including PCD plates up to 125 mm and thick SCD substrates up to 10 mm, enabling scale-up of the angled-etching process for higher throughput or integrated MEMS arrays.
- Precision Metalization Services: The paper utilized Au electrodes. 6CCVD offers custom multi-layer metal stacks (e.g., Ti/Pt/Au, Ti/Pd, W, Cu) deposited in-house, engineered for optimized adhesion and low residual film stress, which is critical for maximizing achievable strain without compromising device integrity.
- Advanced Polishing: To achieve the demonstrated high Q-factors, an ultra-smooth initial surface is mandatory. 6CCVD provides SCD polishing to Ra < 1 nm, significantly superior to standard commercial diamond, ensuring minimal surface scattering and mechanical damping.
Engineering Support
Section titled âEngineering SupportâThe successful design of high-strain MEMS devices requires intricate balancing of geometric factors (length, thickness, gap) against operational constraints (dielectric breakdown, pull-in instability).
- Design Consultation: 6CCVDâs in-house PhD engineering team specializes in the physics of diamond materials for quantum and sensing applications. We offer consultation on material selection, thickness optimization, and stress management for similar QIST MEMS/NEMS projects.
- Supply Chain Reliability: We provide global shipping (DDU default, DDP available), ensuring reliable and timely delivery of complex, custom diamond substrates necessary to maintain aggressive research timelines.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We demonstrate fabrication methods for micro-/nanoelectromechanical systems (MEMS/NEMS) in single-crystal diamond chip.Such devices can be used to study embedded color centers, such as the nitrogen vacancy (NV) or the silicon vacancy (SiV).Color centers have discrete electronic and spin energy levels, which can be controlled by engineering the amount of strain in the diamond lattice.These strain fields can be effectively controlled using conventional MEMS/NEMS devices.As a specific demonstration, we show the tuning of SiV electronic energy levels via static actuation.The device design process accounting for various fundamental and experimental constraints is discussed.