High-temperature Operation Characteristics of Diamond Radiation Detectors

At a Glance

Metadata	Details
Publication Date	2025-05-22
Journal	Sensors and Materials
Authors	Masakatsu Tsubota, Takehiro Shimaoka, Yoshihiro J. Akashi, Shintaro Hirano, Akiyoshi Chayahara
Analysis	Full AI Review Included

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Executive Summary

Demonstrated high-temperature operation of diamond radiation detectors up to 500 °C.
Utilized a guard ring to suppress leakage current at high temperatures, enabling stable detector operation.
Observed charge transport properties comparable to those at room temperature.
Improved hole mobility-lifetime (µτ) product and electron energy resolution at elevated temperatures.
Fabricated detectors using single-crystal CVD diamond synthesized by Hokkaido University (HU) and Element Six Ltd. (E6).
Evaluated cathodoluminescence (CL) spectra to assess crystal quality.
Measured charge distribution induced by 5.486 MeV alpha-particle irradiation.

Technical Specifications

Parameter	Value	Unit	Context
Diamond Band Gap	5.47	eV	Introduction
Methane Concentration	0.2	%	Diamond Synthesis
Chamber Pressure	110	Torr	Diamond Synthesis
Substrate Temperature	900	°C	Diamond Synthesis
Nitrogen Impurities	~1	ppm	Diamond Substrate
Alpha Particle Energy	5.486	MeV	Charge Distribution Measurement
Ti/Pt Electrode Thickness	50	nm	Detector Fabrication
TiC Formation Temperature	400	°C	Detector Fabrication
Operating Temperature (max)	500	°C	High-Temperature Operation
Hole Resolution (23 °C)	0.9	%	Charge Collection Efficiency
Electron Resolution (23 °C)	1.3	%	Charge Collection Efficiency
Hole Resolution (High Temp)	0.6	%	Charge Collection Efficiency
Electron Resolution (High Temp)	0.8	%	Charge Collection Efficiency
Electric Field (HU)	±3.5 x 10³	V/cm	µτ Product Calculation
Electric Field (E6)	±1.0 x 10⁴	V/cm	µτ Product Calculation
µτ (Hole, 500 °C)	2 x 10^-4	cm²/V	Mobility-Lifetime Product
HU Diamond Thickness	85	µm	Sample Dimensions
HU Diamond Area	5 x 5	mm²	Sample Dimensions

Key Methodologies

Diamond Synthesis: Homoepitaxial growth of single-crystal diamond on type-IIa single-crystal diamond substrate using microwave plasma CVD with hydrogen and 0.2% methane mixed gases at 110 Torr and 900 °C substrate temperature.
Detector Fabrication:
- Dichromate treatment to change surface state from hydrogen-terminated to oxygen-terminated.
- Ti/Pt electrode deposition on the as-grown surface.
- Guard ring electrode deposition by photolithography.
- TiC layer formation by vacuum heating at 400 °C for 30 minutes.
Characterization:
- Cathodoluminescence (CL) spectroscopy to evaluate crystal quality.
- Leakage current-applied voltage (I-V) measurements at different temperatures (23 °C, 300 °C, 500 °C) with and without a guard ring.
- Charge distribution measurement under 5.486 MeV alpha-particle irradiation at different temperatures.
- Calculation of mobility-lifetime (µτ) products using Hecht’s equation based on electric field dependence of CCE.

Commercial Applications

Based on the research paper, the following commercial applications can be identified:

Nuclear Instrumentation: Radiation detectors for nuclear fusion reactors (plasma ion temperature measurement).
Nuclear Safety: Radiation detectors for nuclear reactor core atmosphere monitoring and water level meters in pressure vessels.
High-Energy Physics: Radiation detectors for high-energy physics experiments.
Medical Irradiation: Radiation detectors for medical irradiation applications.
Space Environments: Radiation detectors for space applications.

Tech Support

Original Source

DOI: https://doi.org/10.18494/sam5528