Fabrication and Characterization of N-Type Zinc Oxide/P-Type Boron Doped Diamond Heterojunction
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-09-01 |
| Journal | Journal of Electrical Engineering |
| Authors | MariĂĄn Marton, Miroslav MikolĂĄĆĄek, Jaroslav Bruncko, I. ÎovotnĂœ, Tibor IĆŸĂĄk |
| Institutions | Czech Academy of Sciences, Institute of Physics, International Laser Center |
| Citations | 3 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: ZnO/BDD Heterojunctions
Section titled âTechnical Documentation & Analysis: ZnO/BDD HeterojunctionsâExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates the successful fabrication and characterization of a functional wide-bandgap p-n heterojunction using n-type Zinc Oxide (ZnO) and p-type Boron-Doped Diamond (BDD). The findings are highly relevant for engineers developing next-generation transparent electronics, sensors, and high-power devices.
- Core Achievement: Successful fabrication of an optically transparent ZnO/BDD bipolar heterojunction diode.
- Performance Metric: Achieved a rectifying ratio of 55 at ±4 V, confirming functional diode behavior.
- Material Requirement: Success was critically dependent on maintaining very low dopant concentrations in both the BDD and ZnO layers (e.g., B/C ratio limited to 500 ppm in the gas mixture for BDD).
- Material Specification: BDD films were grown to a thickness of 300 nm (0.3 ”m) on Si and UV grade silica glass substrates.
- 6CCVD Value Proposition: 6CCVD specializes in providing highly controlled, electronic-grade Boron-Doped Diamond (BDD) films, essential for achieving the precise, low carrier concentrations required for functional wide-bandgap p-n junctions.
- Customization: 6CCVD offers custom metalization (Ni/Au, Al) and precise thickness control (down to 0.1 ”m) necessary to replicate and scale these heterostructures.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the research paper, detailing the material properties and device performance.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Bandgap | 5.47 | eV | Wide-bandgap semiconductor |
| ZnO Bandgap | 3.37 | eV | Wide-bandgap semiconductor |
| BDD Film Thickness | 300 | nm (0.3 ”m) | Grown via HFCVD |
| Total Heterostructure Thickness | 600 - 700 | nm | ZnO/BDD stack |
| BDD Growth Temperature | 600 | °C | Substrate temperature during HFCVD |
| Optimal B/C Ratio (Gas Mixture) | 500 | ppm | Required for functional p-n junction |
| Rectifying Ratio | 55 | N/A | Measured at ±4 V (I-V curve) |
| BDD Resistivity (Low Doping) | 4.11 x 10-2 | Ωcm | Required for functional diode |
| BDD Resistivity (High Doping) | 1.06 x 10-2 | Ωcm | Near semimetallic transition |
| Ohmic Contact (BDD) | Ni/Au (10/50) | nm | Vacuum annealed at 425 °C |
| Ohmic Contact (ZnO) | Al (100) | nm | Top electrode |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication of the p-n heterojunction relied on precise control over the CVD growth and subsequent sputtering processes.
-
BDD Film Growth (p-type):
- Method: Hot Filament Chemical Vapor Deposition (HFCVD).
- Substrates: Si and UV grade silica glass.
- Gas Mixture: CH4/H2/(H2 + TMB) with 1% CH4 concentration.
- Pressure: 3 kPa.
- Substrate Temperature: Maintained at 600 °C.
- Doping Control: Boron-to-Carbon (B/C) ratio varied from 500 ppm to 15000 ppm in the gas mixture.
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ZnO Film Deposition (n-type):
- Method: RF Sputtering (ZnO:Al target) or Pulsed Laser Deposition (PLD) (ZnO:Al, ZnO:Ga targets).
- Sputtering Parameters: 100 °C, 1.33 Pa Ar pressure, 800 W RF source power.
- PLD Parameters: 5 Pa O2 pressure, temperatures 20 °C (RT), 200 °C, and 400 °C.
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Ohmic Contact Formation:
- BDD Contact: Ni/Au (10/50 nm) double-layer, vacuum annealed (10-3 Pa, 425 °C) for 10 min.
- ZnO Contact: 100 nm Al layer.
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Characterization:
- Raman Spectroscopy (325, 442, and 633 nm laser excitations) to confirm diamond and ZnO phase growth.
- Scanning Electron Microscopy (SEM) for morphology and cross-section analysis.
- Hall constant and 4-point resistivity measurements for electrical property determination.
- Current-Voltage (I-V) measurements to confirm rectifying behavior.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-quality, customized diamond materials required to replicate, optimize, and scale this wide-bandgap heterojunction technology.
Applicable Materials
Section titled âApplicable MaterialsâThe research highlights the critical need for precise, low-level boron doping to ensure semiconducting behavior and functional p-n junction formation.
| Research Requirement | 6CCVD Material Solution | Key Specification Match |
|---|---|---|
| P-type Diamond Film | Boron-Doped Diamond (BDD) PCD | Highly controlled B/C ratio equivalent to 500 ppm gas concentration. |
| Thin Film Structure | Electronic Grade PCD/SCD | Thickness control from 0.1 ”m up to 500 ”m (matching the required 300 nm film thickness). |
| Substrate Compatibility | Custom Substrate Integration | BDD films can be grown on customer-supplied substrates (e.g., Si, SiO2, or UV grade silica glass) or provided as free-standing plates. |
Customization Potential
Section titled âCustomization PotentialâThe success of this heterojunction relies on specific dimensions and contact schemes. 6CCVD offers comprehensive customization services to meet these exact engineering requirements.
- Custom Dimensions: While the paper used small samples, 6CCVD can provide Polycrystalline BDD plates up to 125mm in diameter, enabling large-scale production of these transparent devices.
- Precision Thickness: We guarantee precise thickness control for both Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) films, crucial for optimizing the electrical properties of the 300 nm BDD layer.
- Advanced Metalization: The paper utilized Ni/Au contacts on BDD. 6CCVD offers internal metalization services including Au, Pt, Pd, Ti, W, and Cu. We can replicate the specific Ni/Au (10/50 nm) scheme or develop optimized multi-layer contacts (e.g., Ti/Pt/Au) for enhanced ohmic performance and thermal stability.
- Polishing: For subsequent deposition steps (like the ZnO sputtering), a smooth surface is critical. 6CCVD provides ultra-low roughness polishing: Ra < 1nm (SCD) and Ra < 5nm (Inch-size PCD).
Engineering Support
Section titled âEngineering SupportâThe transition from semimetallic to semiconducting behavior in BDD is a complex material science challenge. 6CCVDâs in-house PhD team provides expert consultation.
- Doping Optimization: Our experts specialize in optimizing MPCVD growth recipes to achieve the precise carrier concentration and resistivity required for functional wide-bandgap heterojunctions, ensuring the material avoids the semimetallic transition observed at high B/C ratios.
- Application Focus: We provide material selection and integration support for similar optically transparent bipolar heterojunction projects, high-power electronics, and diamond-based sensor applications.
- Global Logistics: We offer reliable global shipping (DDU default, DDP available) to ensure prompt delivery of custom diamond wafers worldwide.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Diamond and ZnO are very promising wide-bandgap materials for electronic, photovoltaic and sensor applications because of their excellent electrical, optical, physical and electrochemical properties and biocompatibility. In this contribution we show that the combination of these two materials opens up the potential for fabrication of bipolar heterojunctions. Semiconducting boron doped diamond (BDD) thin films were grown on Si and UV grade silica glass substrates by HFCVD method with various boron concentration in the gas mixture. Doped zinc oxide (ZnO:Al, ZnO:Ge) thin layers were deposited by diode sputtering and pulsed lased deposition as the second semiconducting layer on the diamond films. The amount of dopants within the films was varied to obtain optimal semiconducting properties to form a bipolar p-n junction. Finally, different ZnO/BDD heterostructures were prepared and analyzed. Raman spectroscopy, SEM, Hall constant and I-V measurements were used to investigate the quality, structural and electrical properties of deposited heterostructures, respectively. I-V measurements of ZnO/BDD diodes show a rectifying ratio of 55 at ±4 V. We found that only very low dopant concentrations for both semiconducting materials enabled us to fabricate a functional p-n junction. Obtained results are promising for fabrication of optically transparent ZnO/BDD bipolar heterojunction.