Vertical Diamond p-n Junction Diode with Step Edge Termination Structure Designed by Simulation
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-08-26 |
| Journal | Micromachines |
| Authors | Guangshuo Cai, Caoyuan Mu, Jiaosheng Li, Liuan Li, Shaoheng Cheng |
| Institutions | State Key Laboratory of Superhard Materials, Guangdong Polytechnic Normal University |
| Citations | 4 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Vertical Diamond p-n Junction Diodes
Section titled âTechnical Documentation & Analysis: Vertical Diamond p-n Junction DiodesâExecutive Summary
Section titled âExecutive SummaryâThis document analyzes the simulated design of high-performance vertical diamond p-n junction diodes (PNDs) utilizing a hybrid Step Edge Termination (ET) and Junction Termination Extension (JTE) structure. This research is highly relevant to the development of next-generation high-power, high-frequency diamond electronics.
- Core Achievement: Simulation demonstrated a maximum Breakdown Voltage (VBD) of 2200 V and a Baligaâs Figure of Merit (BFOM) of 12.74 GW/cm2, significantly exceeding conventional diamond diode designs.
- Design Innovation: The hybrid structure combines a shallow Step Mesa ET with a highly doped JTE layer to effectively suppress electric field crowding at the junction edges.
- Material Requirement: The device relies on precise, multi-layer Single Crystal Diamond (SCD) epitaxy, including heavily doped p+ and n+ contact layers and a lightly doped 5 ”m p- drift layer.
- Critical Parameter: Optimal performance was achieved using a JTE doping concentration of 2 × 1022 cm-3, requiring ultra-heavy doping capabilities.
- Operating Conditions: Simulations were conducted at 550 K (277 °C), confirming diamondâs suitability for high-temperature power applications where dopant ionization is maximized.
- 6CCVD Value Proposition: 6CCVD is uniquely positioned to supply the high-quality, custom-thickness SCD wafers and advanced doping required to fabricate and validate these simulated high-voltage devices.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the key performance metrics and structural parameters derived from the optimized simulation results (PND with Step ET (W=1.0 ”m, D=0.5 ”m) and JTE (2 × 1022 cm-3)).
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Breakdown Voltage (VBD) | 2200 | V | Optimized Step ET + JTE PND |
| On-Resistance (Ron) | 0.415 | mΩ·cm2 | Deduced by I-V curve analysis |
| Baligaâs Figure of Merit (BFOM) | 12.74 | GW/cm2 | Highest reported value in this study |
| Turn-On Voltage (Von) | 5.4 - 5.5 | V | Consistent across most designs |
| Simulation Temperature | 550 | K | Used to achieve low resistance |
| p+ Contact Layer Thickness | 500 | nm | Heavily doped bottom layer |
| p- Drift Layer Thickness | 5 | ”m | Critical layer for sustaining reverse bias |
| n+ Contact Layer Thickness | 500 | nm | Heavily doped top layer |
| p+ Doping Concentration | 2 × 1020 | cm-3 | Acceptor concentration |
| p- Doping Concentration | 1.5 × 1015 | cm-3 | Drift layer concentration |
| JTE Doping Concentration (Optimal) | 2 × 1022 | cm-3 | Required for effective field dispersion |
Key Methodologies
Section titled âKey MethodologiesâThe research utilized Silvaco TCAD simulation (Version 5.0.10.R) to optimize the vertical diamond PND structure. The key steps and models employed were:
- Device Structure Definition: Four primary structures were compared: Ideal Parallel-Plane PND, Conventional PND, Simple Step ET PND, and Hybrid Step ET + JTE PND.
- Material Models: Standard diamond semiconductor properties were used, including a 5.5 eV bandgap and high thermal conductivity (22 W/(cm·K)).
- Physical Models: The simulation incorporated several advanced models critical for diamond device accuracy:
- Common phonon-assisted tunneling model.
- Parallel-Electric-Field-dependent mobility model.
- Selberherrâs ionization model.
- Incomplete ionization model (due to high activation energy of diamond dopants).
- Dopant Activation: Acceptor (0.36 eV) and donor (0.57 eV) activation energies were set. A high simulation temperature (550 K) was selected to ensure effective dopant ionization and low resistance.
- Optimization Parameters: The width (W) and depth (D) of the step mesa, and the doping concentration of the JTE layer, were systematically varied to maximize VBD and BFOM.
- Performance Extraction: Current-Voltage (I-V) curves were used to calculate current density, turn-on voltage (Von), and on-resistance (Ron). Electric field distributions were analyzed under VBD conditions to confirm field crowding suppression.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research validates a critical design pathway for high-voltage diamond power electronics. 6CCVD provides the necessary MPCVD diamond materials and precision engineering services required to transition these simulated designs into high-performance physical devices.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend this high-voltage PND research, 6CCVD recommends the following materials, leveraging our expertise in controlled doping and epitaxy:
| Device Layer Requirement | 6CCVD Material Solution | Key Capability Match |
|---|---|---|
| p- Drift Layer (5 ”m) | Electronic Grade SCD | Required thickness (up to 500 ”m available) and ultra-low defect density for high VBD. |
| p+ and n+ Contact Layers | Heavily Doped SCD | Precise control over high doping concentrations (2 × 1020 cm-3 range) for low contact resistance. |
| JTE Layer (2 × 1022 cm-3) | Heavy Boron Doped Diamond (BDD) | Our BDD capability ensures the ultra-high doping concentration required for the JTE to effectively adjust the electric field distribution. |
Customization Potential
Section titled âCustomization PotentialâThe success of the Step ET + JTE structure hinges on precise dimensional control and advanced processing, areas where 6CCVD excels:
- Custom Dimensions: While the simulation used small dimensions, 6CCVD can provide SCD plates and PCD wafers up to 125mm in diameter, enabling scaling for commercial power device fabrication.
- Precision Etching & Mesa Formation: The Step ET requires highly controlled etching depth (D) and width (W). 6CCVD offers advanced laser cutting and processing services to achieve the necessary micron-level precision for mesa and step structures.
- Metalization Services: Real-world PNDs require robust ohmic contacts. 6CCVD offers in-house custom metalization using materials such as Ti, Pt, and Au, which are standard for diamond contacts, ensuring low contact resistance and high thermal stability.
- Thickness Control: The critical 5 ”m drift layer thickness is well within our standard SCD thickness range (0.1 ”m - 500 ”m), guaranteeing the material quality needed to sustain the high reverse bias (2200 V).
Engineering Support
Section titled âEngineering SupportâThe optimization of diamond power devices, particularly the complex interplay between doping, layer thickness, and termination geometry, requires deep material science expertise.
- Application Focus: 6CCVDâs in-house PhD team specializes in material selection and optimization for High-Voltage Diamond Power Devices and High-Temperature Electronics.
- Replication and Extension: We offer consultation services to assist researchers in translating the simulated Step ET + JTE parameters (W, D, JTE concentration) into viable epitaxial growth recipes and fabrication processes.
- Global Supply Chain: We ensure reliable, global delivery of custom diamond materials via DDU default shipping, with DDP options available upon request.
Call to Action: For custom specifications or material consultation regarding the fabrication of high-voltage diamond p-n junction diodes, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In this paper, diamond-based vertical p-n junction diodes with step edge termination are investigated using a Silvaco simulation (Version 5.0.10.R). Compared with the conventional p-n junction diode without termination, the step edge termination shows weak influences on the forward characteristics and helps to suppress the electric field crowding. However, the breakdown voltage of the diode with simple step edge termination is still lower than that of the ideal parallel-plane one. To further enhance the breakdown voltage, we combine a p-n junction-based junction termination extension on the step edge termination. After optimizing the structure parameters of the device, the depletion regions formed by the junction termination extension overlap with that of the p-n junction on the top mesa, resulting in a more uniform electric field distribution and higher device performance.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
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