Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2018-01-01 |
| Journal | EPJ Web of Conferences |
| Authors | O. Obraztsova, Laurent Ottaviani, A. Klix, Toralf Döring, Olivier Palais |
| Institutions | Institut des Matériaux, de Microélectronique et des Nanosciences de Provence, Karlsruhe Institute of Technology |
| Citations | 9 |
| Analysis | Full AI Review Included |
6CCVD Technical Analysis: MPCVD Diamond for Fast Neutron Detection
Section titled â6CCVD Technical Analysis: MPCVD Diamond for Fast Neutron DetectionâExecutive Summary
Section titled âExecutive SummaryâThis study rigorously validates MPCVD Single Crystal Diamond (SCD) as the superior semiconductor material for fast neutron spectrometry in harsh environments (nuclear reactors, fusion facilities) compared to 4H-SiC. 6CCVD, specializing in high-purity SCD, is positioned to supply the requisite materials needed to replicate and advance this research.
- Performance Superiority: The Single Crystal CVD (sCVD) diamond detector achieved a total count rate 20 times higher (4.8 x 10$^{3}$ c/s) than the 4H-SiC detector (2.46 x 10$^{2}$ c/s) under identical 14.12 MeV neutron irradiation conditions.
- Active Volume Dictates Rate: The significantly higher count rate in diamond is attributed directly to its large active detection volume (500 ”m), enabled by the materialâs superior properties and low leakage current, compared to the space charge region (SCR) limit of 21 ”m in the SiC diode.
- Harsh Environment Resilience: Diamondâs wide band gap (5.5 eV) and high displacement threshold energy (40-50 eV) ensure robust operation and extreme radiation hardness, making it ideal for high-flux, high-temperature (up to 600 °C) applications.
- Spectrometry Confirmation: Both detectors successfully resolved the critical ${}^{12}\text{C}(\text{n}, \alpha_{0})^{9}\text{Be}$ reaction peak (8.4 MeV energy deposition), confirming their utility for fast neutron spectrometry.
- 6CCVD Relevance: Replication requires high-quality, large-thickness SCD wafers (up to 500 ”m or more), custom metalization, and high surface polish, all core capabilities provided by 6CCVD.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Material | Single Crystal CVD (sCVD) | N/A | Capacitor-type detector configuration |
| Diamond Thickness / Active Volume | 500 | ”m | Detector thickness, resulting in high count rate |
| SiC Material | 4H-SiC p$^{+}$n Diode | N/A | Fabricated using 350 ”m n$^{+}$ substrate |
| SiC Space Charge Region (SCR) | 21 | ”m | Active detection volume limit at -120V bias |
| Irradiation Neutron Energy (E$_{n}$) | 14.12 | MeV | Measured at 90° angle from DT source |
| Neutron Flux | 9.4 x 10$^{6}$ | n/(cm$^{2}$s) | Experimental measurement condition |
| Diamond Total Count Rate | 4.8 x 10$^{3}$ | c/s | Measured response for 14.12 MeV neutrons |
| SiC Total Count Rate | 2.46 x 10$^{2}$ | c/s | Measured response for 14.12 MeV neutrons |
| Diamond Band Gap | 5.5 | eV | Superiority over SiC (3.27 eV) |
| Diamond Displacement Threshold Energy | 40-50 | eV | Superior radiation hardness over SiC (20-35 eV) |
| Target Reaction Energy (E$_{dep}$) | 8.4 | MeV | Energy deposited by $\alpha$ + $^{9}\text{Be}$ from ${}^{12}\text{C}(\text{n}, \alpha_{0})^{9}\text{Be}$ |
| Diamond Bias Voltage | +120 | V | Operating condition |
| SiC Bias Voltage | -120 | V | Operating condition |
Key Methodologies
Section titled âKey MethodologiesâThe following parameters define the material sourcing and experimental setup used to compare the fast neutron detection capabilities:
- Diamond Detector: Purchased sCVD single crystal diamond, 500 ”m thick, structured as a capacitor-type solid-state ionization chamber.
- SiC Detector Fabrication: Built on a 350 ”m 4H-SiC n$^{+}$ substrate, requiring growth of a 20 ”m n-type epitaxial layer ($~2\text{x}10^{14}$ cm$^{-3}$ doping) and a 1 ”m p$^{+}$ epitaxial layer ($~10^{19}$ cm$^{-3}$ doping).
- SiC Metalization Stack: Applied via ultrahigh vacuum electron beam evaporation, consisting of a multi-layer ohmic contact (Ni/Ti/Al/Ni, 200 nm), an intermediate metallic contact (Al, 1 ”m), and a protective overmetallization (Ti/Ni/Au, 555 nm).
- Irradiation Source: Deuterium-Tritium (DT) neutron generator providing 14 MeV neutrons.
- Experimental Geometry: Detectors positioned 13 cm from the tritium target, measured at a 90° angle relative to the deuterium beam, resulting in a monoenergetic neutron flux of 9.4 x 10$^{6}$ n/(cm$^{2}$s) at 14.12 MeV.
- Readout Electronics: Signals processed using a CAEN A1422 Charge Sensitive Preamplifier (CSP), followed by an ORTEC amplifier for pulse shaping, and digitized using an Analog to Digital Converter (ADC).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the specialized, high-purity CVD diamond materials necessary to achieve the high count rates and high radiation hardness demonstrated in this research for advanced neutron detection applications.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate the high performance detailed in the paper, especially the maximized active volume, Optical Grade Single Crystal Diamond (SCD) is required.
| 6CCVD Product | Specification | Relevance to Neutron Detection |
|---|---|---|
| Optical Grade SCD | Thickness: 0.1 ”m up to 500 ”m | Necessary for low defect density and maximizing the active detection volume (500 ”m required by research). |
| SCD Substrates | Available up to 10 mm thickness | Allows for stacking or creation of ultra-thick detectors for maximum efficiency in high-energy physics applications. |
| Polishing (SCD) | Ra < 1 nm | Ensures optimal interface quality for thin-film metalization and contact stability in high-radiation environments. |
Customization Potential
Section titled âCustomization PotentialâThe SiC detector utilized complex multi-layer metalization (Ni/Ti/Al/Ni, Al, Ti/Ni/Au). Successful high-performance radiation detectors often rely on specialized contacts for thermal management and electrical stability.
- Custom Metalization Stacks: 6CCVD offers extensive in-house metalization capabilities, including Au, Pt, Pd, Ti, W, and Cu. We can deposit multi-layer stacks optimized for ohmic contact formation, low noise, and high-temperature operation ($> 500 °\text{C}$), which are critical for stable sensor performance in harsh reactor cores.
- Custom Dimensions and Shapes: While the study used a 0.33 cm$^{2}$ diode, 6CCVD offers SCD and PCD wafers up to 125mm. We provide precision laser cutting and patterning services to meet specific device geometry requirements, ensuring compatibility with custom shielding or detector assembly systems.
Engineering Support
Section titled âEngineering SupportâDiamondâs high radiation hardness (up to $4 \text{x} 10^{14}$ n/cm$^{2}$ fluence stability demonstrated in related studies) makes it the material of choice for next-generation nuclear sensors.
- 6CCVDâs in-house PhD team provides expert consultation on material selection, device architecture, and custom diamond growth recipes. We specialize in tuning growth parameters to minimize nitrogen incorporation and lattice defects, thereby maximizing charge collection distance (CCD) and spectroscopic resolution for high-energy fast neutron detection projects.
- We offer support for optimizing the surface preparation and polishing required for subsequent epitaxial growth (for p$^{+}$n structures) or reliable electrode deposition (for capacitor-type detectors).
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C) and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV), wide band gap energy (3.27 eV) and high thermal conductivity (4.9 W/cm·K), SiC can operate in harsh environment (high temperature, high pressure and high radiation level) without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV), higher threshold displacement energy (40-50 eV) and thermal conductivity (22 W/cm·K), which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 10 10 n·s -1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD) diamond detectors irradiated with 14 MeV neutrons at room temperature.