Superconducting Density of States in B-Doped Diamond
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-04-01 |
| Journal | Acta Physica Polonica A |
| Authors | Oleksandr Onufriienko, TomĂĄĆĄ Samuely, Gufei Zhang, J. Vanacken, Xu Zheng |
| Institutions | Institute of Experimental Physics of the Slovak Academy of Sciences, Slovak Academy of Sciences |
| Analysis | Full AI Review Included |
Superconducting Density of States in B-Doped Diamond: 6CCVD Material Analysis and Solutions
Section titled âSuperconducting Density of States in B-Doped Diamond: 6CCVD Material Analysis and SolutionsâThis technical documentation analyzes the findings regarding superconductivity in Boron-Doped Microcrystalline Diamond (BDD) films prepared by Chemical Vapor Deposition (CVD). This analysis serves to benchmark 6CCVDâs advanced MPCVD BDD capabilities against the requirements of fundamental low-temperature physics research.
Executive Summary
Section titled âExecutive Summaryâ- Core Achievement: Boron-doped Microcrystalline Diamond (MCD) films demonstrate robust superconductivity, confirming a critical temperature (Tc) of 7 ± 0.5 K via low-temperature Scanning Tunneling Microscopy/Spectroscopy (STM/S).
- Strong Coupling Observed: The superconducting energy gap (Î) of 1.44 meV results in a high 2Î/kBTc ratio of â 4.8, significantly exceeding the standard BCS weak-coupling value of 3.52, suggesting strong electron-phonon coupling.
- Novel Hard Gap Observation: The study observed a homogeneous, zero-conductance âhard gapâ in a polycrystalline film, a feature previously reported only in highly ordered single-crystal BDD.
- Material Specification: The investigated film was 900 nm thick MCD, synthesized using HFCVD, with a high boron concentration of approximately 1.5 x 1021 cm-3.
- 6CCVD Advantage: 6CCVD specializes in high-quality MPCVD-grown Boron-Doped Diamond (BDD), offering superior control over grain size, thickness (0.1 ”m to 500 ”m), and surface finish (Ra < 5 nm for PCD) necessary to replicate or enhance the homogeneity required for these sensitive quantum measurements.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data was extracted from the experimental results and material characterization presented in the paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Sample Type | Boron-Doped Microcrystalline Diamond | N/A | Thin film, approximately 800 nm mean grain size |
| Film Thickness | 900 | nm | CVD deposition thickness |
| Boron Concentration | 1.5 x 1021 | cm-3 | High doping level necessary for superconductivity |
| Critical Temperature (Tc) | 7 ± 0.5 | K | Superconducting transition temperature |
| Superconducting Energy Gap (Î) | 1.44 | meV | Measured at 0.5 K via differential conductance fits |
| BCS Coupling Ratio (2Î/kBTc) | â 4.8 | N/A | Indicates strong coupling (Standard BCS: 3.52) |
| Lowest Measurement Temperature | 0.5 | K | Required for detailed gap mapping via STM/S |
| Surface Roughness (Maximum Corrugation) | 15-20 | nm | Topography across 500 nm x 500 nm area |
| Best Fit Model Parameter (Pair Breaking) | 0.01 | α (Maki parameter) | Indicates weak pair breaking |
Key Methodologies
Section titled âKey MethodologiesâThe superconducting BDD films were fabricated using Hot Filament Chemical Vapor Deposition (HFCVD) and characterized using advanced low-temperature techniques. 6CCVD utilizes highly controlled Microwave Plasma CVD (MPCVD), which provides enhanced quality and purity necessary for high-specification BDD.
- Growth Method: Hot Filament Chemical Vapor Deposition (HFCVD) was utilized for film growth.
- Substrate Preparation: SiO2/Si substrate was seeded with 15-25 nm diamond particles.
- Process Temperatures: Substrate held at 800 °C; HFCVD filament heated to 2200 °C for gas dissociation.
- Gas Composition: 0.6% CH4 in H2 carrier gas mixture.
- Doping Mechanism: Diborane (B2H6) gas was added to the mixture at a 2% B2H6/CH4 ratio to achieve heavy Boron doping.
- Characterization Setup: Scanning Tunneling Microscopy/Spectroscopy (STM/S) performed using a custom low-temperature head and a commercial cryomagnetic system (T range 0.5-8 K).
- STM Tip Preparation: The tip was 99.99% pure Au wire, treated in situ via controlled collision with a clean Au surface to ensure a flat density of states near the Fermi energy.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is positioned as the ideal material partner to replicate, extend, and industrialize this research, leveraging our precision MPCVD processes, which inherently offer better control over material uniformity and quality than HFCVD. The observation of a homogeneous hard gap demands materials with exceptional consistencyâa core capability of 6CCVDâs MPCVD BDD platform.
| Requirement/Goal (Paper) | 6CCVD Solution & Capability | Technical Advantage for Research |
|---|---|---|
| Material: High Quality Superconducting BDD (1.5 x 1021 cm-3) | Heavy Boron-Doped PCD and SCD Wafers | Precise control of doping levels (up to 1021 cm-3) using MPCVD for superior homogeneity and predictable Tc. |
| Dimensions: Lab-scale sample | Custom Dimensions up to 125mm | Ability to scale experiments onto large-area substrates (up to 5-inch plates) for multi-device prototyping or industrial application testing. |
| Thickness: 900 nm thin film | Custom Thickness: 0.1 ”m - 500 ”m | Capability to manufacture films with high thickness accuracy, ensuring precise quantum confinement characteristics or optimizing for specific tunneling geometries. |
| Surface Finish: Roughness 15-20 nm (Max) | Advanced Polishing (Ra < 5 nm for PCD) | High-specification polishing significantly reduces surface corrugation, improving STM/S signal consistency and spatial resolution across the entire wafer surface. |
| Tip/Contact Needs (Au, Ti/Pt/Au) | Custom Metalization Services | In-house capability for standard (Au, Pt, Pd, Cu) and exotic (Ti, W) metal contacts, essential for integration into cryogenic measurement systems and device fabrication. |
Engineering Support
Section titled âEngineering Supportâ- Application Focus: Our materials are perfectly suited for replicating and extending fundamental research in solid-state superconductivity, quantum computing (using diamond vacancies/doping), and high-frequency electronics.
- Material Selection: 6CCVDâs in-house PhD material science team specializes in tuning MPCVD recipes to meet demanding specifications for Boron-Doped Diamond research, particularly concerning carrier concentration and film morphology required for strong coupling phenomena.
- Process Comparison: While the paper used HFCVD, 6CCVDâs MPCVD BDD offers enhanced quality and purity, which is critical for studies requiring highly uniform superconducting properties, potentially leading to even stronger and more reliable homogeneous hard gap observations.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In the presented work, we investigated the superconducting boron doped diamond polycrystalline film prepared by chemical vapor deposition by means of scanning tunneling microscopy/spectroscopy. Differential conductance spectra measured at various temperatures were used to obtain the values of superconducting critical temperature and energy gap.Comparing various theoretical models fitted to the differential conductance spectra measured at 0.5 K suggests weak pair breaking.However, this cannot account for the high 2â k B T C ratio, which therefore indicates strong coupling.