Diamond as a material for monolithically integrated optical and optomechanical devices (Phys. Status Solidi A 11∕2015)
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2015-11-01 |
| Journal | physica status solidi (a) |
| Authors | Patrik Rath, S. Ummethala, Christoph E. Nebel, Wolfram H. P. Pernice |
| Institutions | Karlsruhe Institute of Technology, University of Münster |
| Citations | 3 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond for Integrated Optomechanics
Section titled “Technical Documentation & Analysis: Diamond for Integrated Optomechanics”Source: Physica Status Solidi A, 212 No. 11 (2015) Feature Article: Diamond as a material for monolithically integrated optical and optomechanical devices Authors: Rath, Ummethala, Nebel, and Pernice
Executive Summary
Section titled “Executive Summary”This feature article highlights the critical role of high-quality MPCVD diamond in enabling next-generation integrated optical and optomechanical devices. 6CCVD specializes in providing the foundational diamond materials required for this advanced research.
- Core Application: Monolithic integration of optical waveguides, photonic crystals, and electrical contacts on a single diamond platform, crucial for quantum and classical sensing.
- Material Requirement: Ultra-high purity, low-stress Single Crystal Diamond (SCD) or high-quality Polycrystalline Diamond (PCD) thin films are necessary to achieve low optical loss and high mechanical Q-factors.
- Device Complexity: The research involves complex structures like Mach-Zehnder interferometers (MZI) and photonic crystal cavities, demanding sub-micron precision patterning and etching.
- Integration Focus: Successful integration requires precise metalization (e.g., Au, Pt, Ti) onto the diamond surface for electrical actuation and signal routing, a core 6CCVD capability.
- Surface Quality: Achieving functional integrated devices necessitates extremely low surface roughness (Ra < 1 nm) to minimize scattering losses in the fabricated waveguides.
- 6CCVD Value Proposition: We provide customized, polished, and metalized MPCVD diamond wafers and thin films, directly supporting the fabrication of high-performance integrated photonics and optomechanical systems.
Technical Specifications
Section titled “Technical Specifications”The following parameters are typical requirements for the fabrication of diamond-based integrated optical and optomechanical devices, inferred from the application context (integrated photonics and MEMS/NEMS).
| Parameter | Value (Inferred) | Unit | Context |
|---|---|---|---|
| Diamond Material Purity | < 5 | ppb N | Required for low optical absorption and NV center creation |
| Device Layer Thickness | 0.1 - 0.5 | µm | Thin film required for high-confinement waveguides |
| Substrate Thickness | 300 - 500 | µm | Standard handling thickness for processing |
| Waveguide Width | 400 - 800 | nm | Single-mode operation, typically near 1550 nm |
| Surface Roughness (Ra) | < 1 | nm | Critical for minimizing optical scattering loss |
| Metalization Stack | Ti/Pt/Au | N/A | Standard ohmic contacts for electrical tuning/actuation |
| Operating Wavelength | 1550 | nm | Common telecom band for integrated photonics |
| Etching Method | O2 Plasma | N/A | Required for high-aspect ratio diamond structuring |
Key Methodologies
Section titled “Key Methodologies”Replicating the advanced monolithic integration demonstrated in this research requires precise control over the diamond material growth and subsequent microfabrication steps.
- High-Purity MPCVD Growth: Growth of high-quality SCD or heteroepitaxial PCD thin films using Microwave Plasma Chemical Vapor Deposition (MPCVD) to ensure low defect density and high optical transparency.
- Substrate Preparation: Achieving a highly polished surface (Ra < 1 nm) on the diamond material prior to device patterning to minimize propagation losses.
- Thin Film Transfer (If Required): Techniques such as laser lift-off or sacrificial layer etching may be employed to create freestanding diamond membranes or thin films on a secondary substrate (e.g., SiO2) for optomechanical devices.
- E-Beam Lithography (EBL): High-resolution patterning of the waveguide and photonic crystal structures, requiring precise alignment and nanoscale feature definition.
- Reactive Ion Etching (RIE): Deep etching of the diamond film using oxygen (O2) plasma to define the high-aspect ratio waveguides and photonic crystal holes.
- Metalization: Deposition of multi-layer metal stacks (e.g., Ti/Pt/Au) via E-beam evaporation or sputtering to create electrical contacts for thermal tuning, actuation, or integration with external electronics.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”6CCVD is uniquely positioned to supply the high-specification diamond materials necessary to replicate and advance research in integrated diamond photonics and optomechanics.
Applicable Materials
Section titled “Applicable Materials”| 6CCVD Material | Description | Relevance to Integrated Devices |
|---|---|---|
| Optical Grade SCD | High-purity, low-birefringence single crystal diamond. | Essential for low-loss waveguides, high Q-factor cavities, and quantum applications (NV centers). |
| Optical Grade PCD | High-quality polycrystalline diamond wafers up to 125mm. | Ideal for large-area integrated circuits and cost-effective scaling of optomechanical sensors. |
| Thin Film SCD/PCD | SCD/PCD layers ranging from 0.1 µm to 500 µm. | Directly meets the requirement for thin device layers necessary for high-confinement photonic structures. |
Customization Potential
Section titled “Customization Potential”The complexity of monolithically integrated devices demands highly customized starting materials. 6CCVD offers end-to-end material engineering support:
- Custom Dimensions: We supply plates and wafers up to 125mm (PCD) and custom-cut SCD pieces, ensuring compatibility with standard semiconductor fabrication tools.
- Precision Polishing: We guarantee ultra-smooth surfaces, achieving Ra < 1 nm on SCD and Ra < 5 nm on inch-size PCD, which is critical for minimizing optical scattering losses in waveguides.
- Advanced Metalization Services: We offer in-house deposition of custom metal stacks, including the Ti/Pt/Au layers commonly used for electrical contacts in optomechanical devices, as well as Au, Pd, W, and Cu.
- Thickness Control: We provide precise thickness control for both SCD and PCD films, from 0.1 µm up to 500 µm, allowing researchers to optimize waveguide confinement and mechanical resonance frequencies.
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team specializes in the material science of MPCVD diamond for advanced applications. We offer consultation services to assist researchers in:
- Selecting the optimal diamond grade (SCD vs. PCD) based on required optical loss, mechanical Q-factor, and device area.
- Designing appropriate metalization schemes for reliable ohmic contact and thermal actuation in integrated optomechanical devices.
- Specifying material parameters (e.g., nitrogen concentration, thickness uniformity) to maximize the performance of photonic crystal cavities and Mach-Zehnder interferometers.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Radiation pressure forces provide new mechanical degrees of freedom to free-standing optical components. In particular in the case of nanophotonic systems such forces enable efficient light-based actuation for tunable devices and superior sensing elements within the framework of optomechanics. The quest to design optimal optomechanical structures for applications in fundamental physics and metrology relies on novel materials with both excellent optical and mechanical properties. These requirements make diamond an excellent choice for the realization of advanced optomechanical devices. Recent progress in this field has led to the demonstration of nanoscale diamond devices with very low dissipation in the mechanical domain, paired with advances in creating high-quality optical resonators and waveguide devices (see the Feature Article by Patrik Rath et al. on pp. 2385-2399). By embedding diamond nanomechanical resonators in nanophotonic circuits a powerful platform is achieved which allows for using the rich toolbox of integrated optics for chipscale systems. This approach is in particular portable to the single photon regime, where diamond also excels because of the availability of single photon emitters in the form of color centers. A unified optomechanical platform with integrated single photon emitters and detectors thus will enable reconfigurable diamond quantum photonic systems on a chip.