About this Research Topic
Semiconductor detectors play a very important role in plasma diagnostics. They can be used to detect neutron-induced charged particles and to monitor neutron beams in generators to count the number of charged particles emitted by deuterium-tritium (D-T) or deuterium-deuterium (D-D) fusion reactions. Semiconductors are typically used for the detection of fast-ion losses, low-energy gammas (1-3 MeV), hard and soft x-rays (50-500 keV and 2-30 keV, respectively), and UV light. Unfortunately, neutron radiation introduces various defects into semiconductors, induces serious degradation in performance, and considerably shortens the lifetime of radiation detectors. Thus, it is important to develop robust detectors that survive the high radiation fluences and high temperature environment expected in plasma diagnostics.
The fusion energy method, when controlled, is extremely efficient and uses extremely abundant materials. The waste produced is far less, in both quantity and risk, compared to both fossil fuel and nuclear fission reactors. However, due to the specific conditions: extremely high temperatures and neutron irradiation from the plasma, required for fusion to occur, the existing diagnostics and measurement systems simply will not perform as needed. This extreme harsh environment, such as related to ionizing radiation and high temperature conditions, can seriously degrade electronic devices. For example, the radiation levels in next-generation fusion reactors, such as ITER, can severely compromise or even cause permanent failure of many key diagnostics devices that are presently used in D-D magnetically confined fusion plasma devices.
Wide bandgap semiconductors (WBG), such as SiC, diamond or GaN, offer reduced leakage current when compared to silicon, which maintains low noise levels even at high temperatures and after irradiation at high fluences. For example, recent technology improvements, driven mainly by the power devices industry, in the production of the SiC material, offer the possibility of using thick substrates and fabricating structures with small pitch electrodes on large active detection surfaces. This allows the fabrication of innovative radiation detectors in WBG that will be the only detectors capable of withstanding high radiation fluences and will be operated without cooling. Furthermore, this subject matter is relevant to space applications (ESA), homeland security, HEP experiments (such as at CERN) and environmental monitoring.
Keywords: SiC, GaN, wide bandgap semiconductor detectors, radiation detectors, harsh environments, radiation damage, simulation
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