All‐Optical Electric Field Sensing with Nanodiamond‐Doped Polymer Thin Films
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2025-07-24 |
| Journal | Advanced Functional Materials |
| Authors | R.C. Styles, Mengke Han, Toon Goris, J. G. Partridge, Brett C. Johnson |
| Institutions | RMIT University, The University of Adelaide |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: All-Optical Electric Field Sensing in Diamond
Section titled “Technical Documentation & Analysis: All-Optical Electric Field Sensing in Diamond”Executive Summary
Section titled “Executive Summary”This research successfully demonstrates a robust, all-optical method for electric field sensing using Nitrogen-Vacancy (NV) centers embedded in fluorescent nanodiamonds (FNDs) within a solid-state capacitor device. This breakthrough is highly relevant to 6CCVD’s mission to supply high-quality MPCVD diamond for integrated quantum and classical sensing applications.
- Solid-State Sensing Validation: Confirms the viability of NV charge state modulation (NV⁰ $\rightarrow$ NV⁻ conversion) as a reliable mechanism for electric field sensing in integrated solid-state systems, eliminating the need for complex microwave (MW) spin control.
- High Sensitivity Achieved: Demonstrated an electric field sensitivity of 19 V cm⁻¹ Hz⁻¹/² for FNDs, which is competitive with or superior to previous ODMR-based methods in nanodiamonds.
- Ultrafast Response Dynamics: Observed a rapid, transient increase in NV⁻ photoluminescence (PL) intensity (up to 31%) within 0.1 ms of voltage application, confirming fast charge state dynamics suitable for high-speed sensing.
- Material Dependence: The mechanism relies critically on the presence of substitutional nitrogen (N$_{s}^{0}$) defects acting as electron donors, highlighting the necessity of precise nitrogen doping control in the diamond source material.
- Integrated Platform: The device structure (ITO/Polymer/FND/Cr/Au) provides a clear pathway for miniaturization and integration of diamond sensors into microelectronic circuits, a key target market for 6CCVD’s custom SCD and PCD wafers.
Technical Specifications
Section titled “Technical Specifications”Data extracted from the research paper detailing key performance metrics and material parameters.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Electric Field Sensitivity (FND) | 19 | V cm⁻¹ Hz⁻¹/² | Shot-noise-limited, single FND |
| Maximum PL Intensity Change (Transient) | 31 | % | NV⁻ PL increase upon 100 V application |
| Response Time (Transient Peak) | 0.1 | ms | Time to reach maximum PL increase |
| Applied Voltage (V$_{on}$) | +100 | V | Used for primary PL measurements |
| Maximum Electric Field (E) | 625 | kV cm⁻¹ | Calculated field across the FND layer |
| FND Particle Size | 100 | nm | Hydrogenated nanodiamonds used |
| SCD/PCD Layer Thickness (PVP-FND) | 0.416 ± 0.010 | µm | Average film thickness, low roughness |
| Excitation Wavelength | 532 | nm | Continuous-wave (CW) laser |
| Excitation Power Range | 30 to 900 | µW | Used to study charge state dynamics |
| Measured Capacitance (Operational Freq) | 0.416 | nF | Measured at ~67 Hz |
| Bulk Nitrogen Concentration (N$_{s}^{0}$) | 10 | ppm | Estimated concentration in FND bulk |
Key Methodologies
Section titled “Key Methodologies”The experiment involved the fabrication of a multilayer capacitor device incorporating FNDs and subsequent optical characterization under pulsed voltage.
- Substrate Preparation: Indium-Tin-Oxide (ITO) coated glass (18 x 18 mm) was used as the transparent conductive substrate electrode.
- Dielectric Layer Deposition (POD): A 250 nm layer of Poly-octadiene (POD) was deposited via plasma polymerization (10⁻⁴ mbar chamber pressure, 50 W power).
- FND Integration: 100 nm hydrogenated FNDs (0.25 mg mL⁻¹ concentration) were dispersed in a Polyvinylpyrollidone (PVP) solution. This solution was spin-coated (1800 RPM) onto the POD layer, resulting in a PVP-FND film thickness of 0.416 µm.
- Top Electrode Fabrication: A second POD layer was deposited, followed by the sputtering of a 50 nm thick Chromium/Gold (Cr/Au) top electrode.
- Optical Setup: A custom confocal fluorescence microscope was used, employing a 532 nm CW laser (200 µW) and a 100x objective (NA = 0.90).
- Spectral Filtering: Photoluminescence (PL) was spectrally separated using filters for NV⁻ detection (700-900 nm) and NV⁰ detection (550-650 nm).
- Voltage Pulsing: A square wave voltage pulse (+100 V for 15 ms, 0 V for 30 ms) was applied via a custom PCB and operational amplifier, with PL acquisition synchronized at a 10 kHz rate (0.1 ms bins).
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”This research validates the critical role of high-quality, doped diamond material in developing next-generation solid-state quantum sensors. 6CCVD is uniquely positioned to supply the advanced MPCVD diamond required to transition this technology from nanodiamond suspensions to robust, integrated wafer platforms.
Applicable Materials for Replication and Extension
Section titled “Applicable Materials for Replication and Extension”The observed electric field sensing relies on the efficient conversion of NV⁰ to NV⁻, driven by the presence of substitutional nitrogen (N$_{s}^{0}$) acting as an electron donor. 6CCVD offers materials with precisely controlled doping to optimize this mechanism in a stable, bulk format.
| Research Requirement | 6CCVD Material Solution | Key Benefit for Application |
|---|---|---|
| Controlled N$_{s}^{0}$ Concentration | Nitrogen-Doped SCD or PCD | We offer MPCVD diamond with controlled nitrogen concentrations (up to 100 ppm) to maximize the availability of electron donors necessary for rapid NV charge state cycling. |
| Integrated Sensing Platform | Optical Grade SCD Wafers | SCD provides superior crystal quality (Ra < 1 nm polished) and low defect density, ideal for near-surface NV creation and integration into high-performance optical devices. |
| Large-Area Sensor Arrays | Inch-Size PCD Plates | We supply Polycrystalline Diamond (PCD) wafers up to 125 mm in diameter, enabling the scale-up of these solid-state capacitor devices for commercial array manufacturing. |
| Electrochemical Sensing Extension | Boron-Doped Diamond (BDD) | For extending this work into electrochemical or pH sensing (as referenced in the paper), BDD films offer excellent conductivity and chemical inertness, available in custom thicknesses (0.1 µm to 500 µm). |
Customization Potential for Integrated Devices
Section titled “Customization Potential for Integrated Devices”The paper highlights the need for precise thin-film deposition and electrode integration. 6CCVD provides comprehensive post-processing services to meet these engineering demands:
- Custom Dimensions and Thickness: While the FND layer was 0.416 µm, 6CCVD can supply SCD and PCD plates ranging from 0.1 µm to 500 µm thick, allowing researchers to optimize the diamond layer for maximum electric field penetration and sensing volume.
- Advanced Metalization Services: The device utilized Cr/Au electrodes. 6CCVD offers in-house deposition of standard and custom metal stacks, including Au, Pt, Pd, Ti, W, and Cu, ensuring robust, low-resistance contacts essential for high-frequency voltage pulsing.
- Precision Machining: We provide laser cutting and polishing (Ra < 5 nm for inch-size PCD) to achieve the precise geometries and surface quality required for lithographic patterning and integration into complex PCB or microfluidic architectures.
Engineering Support
Section titled “Engineering Support”The transition from nanodiamonds (FNDs) to bulk or thin-film MPCVD diamond requires expertise in surface chemistry and defect engineering.
- Surface Termination Control: The paper emphasizes the role of hydrogen termination in near-surface band bending and charge state modulation. Our in-house PhD team provides consultation on achieving and maintaining specific surface terminations (e.g., H-terminated or O-terminated) to optimize NV charge state stability and electric field response for similar all-optical voltage sensing projects.
- Defect Optimization: We assist researchers in selecting the optimal diamond growth recipe to control the ratio of NV⁻ to NV⁰ and the concentration of N$_{s}^{0}$ donors, ensuring maximum sensing efficiency and signal-to-noise ratio (SNR).
- Global Logistics: 6CCVD ensures reliable, global shipping (DDU default, DDP available) of sensitive diamond materials, supporting international research and development efforts.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract The nitrogen‐vacancy (NV) center is a photoluminescent defect in diamond that exists in different charge states, NV ‐ and NV 0 , that are sensitive to the NV’s nanoscale environment. Here, all‐optical voltage sensing with NV centers in fluorescent nanodiamonds (FNDs) is demonstrated in a solid‐state device based on electric field‐induced NV charge state modulation. More than 95% of FNDs integrated into a polymer‐based capacitor device show a transient increase in NV − PL intensity up to 31% within 0.1 ms after application of an external voltage, accompanied by a simultaneous decrease in NV 0 PL. The NV − PL signal increases with increasing electric field from 0 to 619 kV cm −1 . The best electric field sensitivity for a single FND is 18 V cm −1 Hz −½ . The NV charge state photodynamics are investigated on the millisecond timescale. The change in NV PL is found to strongly depend on the rate of photoexcitation. A model is proposed that qualitatively explains the results based on an electric field‐induced redistribution of photoexcited electrons from substitutional nitrogen to NV centers, leading to a transient conversion of NV 0 to NV − centers. These results contribute to the development of FNDs as reliable, all‐optical, nanoscale electric field sensors in solid‐state systems.