Demonstration of electric double layer gating under high pressure by the development of field-effect diamond anvil cell
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-06-01 |
| Journal | Applied Physics Letters |
| Authors | Shintaro Adachi, Ryo Matsumoto, Sayaka Yamamoto, Takafumi D Yamamoto, Kensei Terashima |
| Institutions | Hokkaido University, National Institute for Materials Science |
| Citations | 4 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research details the successful development and demonstration of a novel hybrid device, the Electric Double Layer Transistor-Diamond Anvil Cell (EDLT-DAC), designed to explore unknown physical phenomena by simultaneously controlling carrier density and applying high pressure.
- Core Innovation: The EDLT-DAC combines the high-pressure generation capability of a Diamond Anvil Cell (DAC) with the efficient carrier tuning of an Electric Double Layer Transistor (EDLT).
- Demonstration: The device successfully induced an electrical field-effect in a Bismuth (Bi) thin film, demonstrating carrier density control under pressures up to 1.95 GPa.
- Key Mechanism: The ionic liquid electrolyte (DEME-TFSI) functions effectively as both the pressure medium and the gating medium.
- EDL Stabilization: A critical finding is that high pressure stabilizes the Electric Double Layer (EDL). Above the estimated glass transition pressure (PG), the resistance state induced by the gate voltage is maintained even after the voltage is removed.
- Device Components: The device utilizes a custom DAC with boron-doped diamond electrodes and a Pt(80%)-Ir(20%) alloy gasket, which serves as the gate electrode.
- Scientific Value: The EDLT-DAC provides a powerful, alternative route to control electronic structure, bypassing chemical doping, and is highly promising for the search for High Transition-Temperature Superconductivity (HTS).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Applied Pressure (P) | 1.95 | GPa | Maximum pressure achieved during field-effect measurement. |
| Gate Voltage (VG) Range | 0 to 1 | V | Voltage applied between the Pt-Ir gate and the source electrode. |
| Leakage Current Limit | < 20 | nA | Maximum current flowing through the DEME-TFSI electrolyte. |
| Sample Material | Bismuth (Bi) | Film | Thin film prepared by vapor deposition. |
| Bi Film Thickness | 60 - 70 | nm | Thickness evaluated by atomic force microscopy. |
| Electrolyte / Pressure Medium | DEME-TFSI | Ionic Liquid | N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide. |
| Gate Electrode Material | Pt(80%)-Ir(20%) | Alloy | Used as the gasket; chosen for electrochemical stability and hardness (HV = 240). |
| Gasket Thickness | 200 | ”m | Thickness of the Pt-Ir sheet. |
| Lower Anvil Electrodes | Boron-doped | Diamond | Used for source and drain contacts. |
| Estimated Glass Transition Pressure (PG) | 1.54 to 1.92 | GPa | Pressure range at Room Temperature (RT) where EDL stabilization was observed. |
| Resistance Reduction (Ambient P) | 510 to 100 | Ω | Resistance change upon application of VG = 1 V at ambient pressure. |
Key Methodologies
Section titled âKey MethodologiesâThe EDLT-DAC was constructed and operated using the following key steps and components:
- Diamond Anvil Cell (DAC) Fabrication: The device utilized a custom DAC base. The lower anvil featured micro-scale boron-doped diamond electrodes (acting as source and drain) and an insulating un-doped diamond layer. The upper anvil had a culet diameter of 600 ”m.
- Sample Integration: A Bismuth (Bi) thin film (60-70 nm) was prepared via vapor deposition directly onto the lower diamond anvil, connecting to the diamond electrodes.
- Gate Electrode Setup: A 200 ”m thick sheet of Pt(80%)-Ir(20%) alloy was employed as the gasket. This alloy served the dual function of sealing the sample space under pressure and acting as the electrochemically stable gate electrode.
- Electrolyte Injection: The sample space was filled with the ionic liquid DEME-TFSI, which acts as the pressure medium and the electrolyte necessary for forming the Electric Double Layer (EDL).
- Pressure Application and Measurement: Pressure was applied by pressing the anvils and was evaluated in situ using the peak position of the R1 ruby fluorescence line (Piermariniâs equation).
- Electrical Gating: A positive gate voltage (VG = 1 V) was applied between the Pt-Ir gate and the source electrode. This attracted cations to the sample surface, inducing electrons in the Bi film channel (field-effect).
- Resistance Monitoring: Electrical resistance was measured using a standard four-probe method across a temperature range of 300 K down to 2 K.
Commercial Applications
Section titled âCommercial ApplicationsâThe development of the EDLT-DAC and the discovery of pressure-stabilized EDL offer significant potential for advanced materials research and device engineering:
- Advanced Materials Discovery:
- Accelerating the systematic search for novel superconducting materials (HTS) by mapping the phase space defined by pressure and carrier concentration.
- Exploring intrinsically unstable phases in materials that cannot be reached through conventional chemical doping or ambient-pressure field-effect methods.
- Non-Volatile Memory and Transistors:
- The observation that high pressure stabilizes the EDL, maintaining the induced carrier state even after VG is removed, suggests a pathway for developing non-volatile field-effect transistors (FETs).
- This stabilization effect could lead to new forms of high-density, low-power memory devices operating under specific pressure or glass-like conditions.
- Extreme Environment Electronics:
- Designing and testing electronic components (e.g., sensors, switches, logic circuits) capable of functioning reliably under high hydrostatic pressure, relevant for deep-sea or geological exploration equipment.
- Fundamental Physics Tooling:
- The EDLT-DAC provides a unique, quantitative tool for studying the interplay between mechanical strain (pressure) and electronic structure (carrier density) in condensed matter systems.
View Original Abstract
We have developed an approach to control the carrier density in various materials under high pressure by the combination of an electric double layer transistor (EDLT) and a diamond anvil cell (DAC). In this study, this âEDLT-DACâ was applied to a Bi thin film, and here, we report the field effect under high pressure in the material. Our EDLT-DAC is a promising device for exploring unknown physical phenomena such as high transition-temperature superconductivity.