Magnetic Control of Magneto-Electrochemical Cell and Electric Double Layer Transistor
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-08-30 |
| Journal | Scientific Reports |
| Authors | Takashi Tsuchiya, Masataka Imura, Yasuo Koide, Kazuya Terabe |
| Institutions | National Institute for Materials Science |
| Citations | 23 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: Magnetic Control of Magneto-Electrochemical Devices
Section titled âTechnical Analysis and Documentation: Magnetic Control of Magneto-Electrochemical DevicesâExecutive Summary
Section titled âExecutive SummaryâThe research details the novel development and operation of Magneto-Electrochemical Cells (MECs) and Magnetic Field Effect Transistors (MFETs) using hydrogen-terminated diamond thin films, controlled purely by applied magnetic fields rather than conventional electric fields. This advancement opens new pathways for remote electrochemical control and sensing applications.
- Novel Operating Principle: Demonstrated magnetic control of ionic transport using the paramagnetic properties of diluted [Bmim]FeClâ electrolyte, successfully operating MECs and MFETs.
- High-Performance Material: Utilized Hydrogen-Terminated (H-Terminated) Epitaxial Diamond grown via Microwave Plasma Chemical Vapor Deposition (MPCVD) as the channel material for the MFET/EDLT device.
- Significant EMF Generation: MECs composed of Au/Au electrodes achieved a substantial maximum Electromotive Force (EMF) of 130 mV using a small neodymium magnet (200-300 mT field required for operation).
- Extreme Magnetoresistance (MR): The MFET exhibited a colossal room-temperature magnetoresistance switching ratio up to 503%, achieved by magnetically modulating the hole concentration in the diamond 2D Hole Gas (2DHG).
- Advanced Fabrication: The diamond channel required precise homoepitaxial MPCVD growth (500 nm thick layer) followed by patterned UV-ozone treatment and custom multi-layer metalization (Pd/Ti/Au) for electrodes.
- Future Relevance: This methodology provides a path to developing novel electrochemical devices free from the structural and material limitations imposed by conventional electrical contacts.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points define the core physical and performance metrics extracted from the research on MEC and MFET devices.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Max EMF (MEC) | 130 | mV | Achieved at 50% [Bmim]FeClâ dilution (Au/Au electrodes) |
| Required H-Field (Operation) | 200 - 300 | mT | Minimum field sufficient to operate devices |
| Applied H-Field (Max Test) | 480 | mT | Used for high-performance optical and electrical characterization |
| MFET Switching Ratio (MR) | Up to 503 | % | Maximum observed Magnetoresistance at room temperature (298 K) |
| Diamond Growth Method | Homoepitaxial MPCVD | N/A | Growth on Ib-type HPHT (100) SCD substrates |
| Epitaxial Layer Thickness | 500 | nm | Target thickness of the hydrogen-terminated SCD channel |
| MFET Channel Dimensions | 500 long, 800 wide | ”m | UV-ozone defined channel geometry |
| Deposition Temperature | 1213 | K | MPCVD processing temperature |
| H-Termination Treatment Temp | 353 | K | UV-ozone process temperature |
| Source/Drain Metal Stack (MFET) | Pd (10)/Ti (10)/Au (200) | nm | Deposited via electron beam evaporation |
Key Methodologies
Section titled âKey MethodologiesâThe successful fabrication of the high-performance MFET device relies heavily on precise control over MPCVD growth and surface engineering of the diamond thin film.
- SCD Substrate Preparation: Utilization of Ib-type high-pressure high-temperature (HPHT) single crystal diamond (100) orientation substrates.
- Epitaxial Diamond Growth: Homoepitaxial deposition of a 500 nm thick diamond thin film using MPCVD, maintaining high purity and crystal quality.
- Recipe Parameters: Hâ flow 1000 sccm; CHâ flow 0.5 sccm.
- Temperature: Deposition sustained at 1213 K.
- Channel Definition and Surface Termination: The p-type 2DHG layer was formed via hydrogen termination.
- The channel area (500 ”m x 800 ”m) was patterned.
- Insulating regions surrounding the channel were formed by UV-ozone treatment (oxygen termination) at 353 K for 20 minutes.
- Electrode Metalization: Source and drain electrodes were deposited onto the H-terminated surface via electron beam evaporation, using a custom tri-layer stack:
- Palladium (Pd): 10 nm
- Titanium (Ti): 10 nm
- Gold (Au): 200 nm
- Electrolyte Application: Devices were covered in epoxy resin (excluding the channel) and immersed in the active electrolyte: 50% diluted [Bmim]FeClâ solution.
- Magnetic Control: Device operation (current modulation) was achieved by applying a magnetic field (up to 480 mT) using neodymium magnets to induce concentration gradients of the paramagnetic FeClââ» ions.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the advanced MPCVD diamond materials and engineering services required to replicate and extend this breakthrough research in magneto-electrochemical devices.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate the MFET structure and performance, researchers require high-quality, defect-managed, single-crystal diamond material.
- Electronic Grade SCD Wafers (100) Orientation: 6CCVD provides high-purity Single Crystal Diamond (SCD) material grown via MPCVD, essential for forming the high-mobility 2D Hole Gas (2DHG) layer upon H-termination. We specialize in custom growth on Ib-type HPHT or highly purified SCD substrates.
- Epitaxial Layer Thickness Control: The 500 nm epitaxial layer thickness is precisely within 6CCVDâs standard SCD thickness range (0.1 ”m - 500 ”m). We guarantee tight tolerance on custom thickness specifications required for optimized 2DHG formation.
Customization Potential
Section titled âCustomization PotentialâThe success of the MFET relies on non-standard dimensions, a specific metal stack, and ultra-smooth surfaces, all core capabilities of 6CCVD.
| Service Category | Requirement in Paper | 6CCVD Capability |
|---|---|---|
| Dimensions & Geometry | 500 ”m x 800 ”m channel dimensions. | Custom dimensions for plates and wafers up to 125 mm. Advanced Laser Cutting Services enable precise definition of micro-scale channel geometries and electrode positioning. |
| Surface Quality | High-quality epitaxial growth required for stable H-termination and 2DHG. | Ultra-Smooth Polishing: Achieved surface roughness Ra < 1 nm for SCD wafers, critical for consistent H-termination and minimizing scattering at the electrode/electrolyte interface. |
| Custom Metalization | Required tri-layer stack: Pd (10 nm) / Ti (10 nm) / Au (200 nm). | In-House Metal Deposition: 6CCVD offers custom metalization of Au, Pt, Pd, Ti, W, and Cu, providing precise control over layer thickness and material selection necessary for optimized ohmic contacts to H-terminated diamond. |
| Alternative Doping | N/A (Undoped/H-Terminated used). | For extension projects requiring higher conductivity or alternative gates, 6CCVD offers Boron-Doped Diamond (BDD) thin films for use as conductive electrodes or specialized channel layers. |
Engineering Support
Section titled âEngineering SupportâThis research demonstrates a powerful method for integrating diamond material into advanced magneto-ionic and electrochemical systems.
6CCVDâs in-house team of PhD material scientists and technical engineers offers expert support for projects involving:
- Magneto-Ionic Devices: Consulting on material selection and surface preparation for devices exploiting external magnetic field control over electrolytes.
- High-Performance FETs and EDLTs: Assistance in optimizing diamond epitaxial growth parameters (e.g., doping levels, termination methods) to maximize carrier mobility and switching ratios in devices like the 503% MR MFET shown here.
- Novel Energy Storage/Sensing: Guidance on integrating SCD and PCD into applications such as advanced concentration cells, resistive memory, and solid-state battery technology.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract A magneto-electrochemical cell and an electric double layer transistor (EDLT), each containing diluted [Bmim]FeCl 4 solution, have been controlled by applying a magnetic field in contrast to the control of conventional field effect devices by an applied electric field. A magnetic field of several hundred mT generated by a small neodymium magnet is sufficient to operate magneto-electrochemical cells, which generate an electromotive force of 130 mV at maximum. An EDLT composed of hydrogen-terminated diamond was also operated by applying a magnetic field. Although it showed reversible drain current modulation with a magnetoresistance effect of 503%, it is not yet advantageous for practical application. Magnetic control has unique and interesting characteristics that are advantageous for remote control of electrochemical behavior, the application for which conventional electrochemical devices are not well suited. Magnetic control is opening a door to new applications of electrochemical devices and related technologies.