4H-SiC Detectors Research Articles

Highly sensitive UV detector based on the transverse Dember effect of 4H-SiC single crystal

In this work, voltage-mode passive ultraviolet (UV) detectors have been designed and fabricated based on the transverse Dember effect of c-axis tilted n-type 4H-SiC single crystals, which may solve the disadvantages of traditional UV detectors with inadequate sensitivity and stability. A sensitivity as high as 96 000 μV/W has been identified in such 4H-SiC detectors via the transverse Dember effect under the illumination of UV light with a wavelength of 365 nm, which significantly exceeds those of traditional UV detectors based on the transverse thermoelectric effect. In addition, the rise time and decay time of 1.0 and 10.2 ms have been determined in these 4H-SiC detectors, respectively, which are much smaller than those of the current-mode detectors. These results may provide an approach to fabricate the high-performance UV detectors with low cost.

250 μm Thick Detectors for Neutron Detection: Design, Electrical Characteristics, and Detector Performances

Solid State Detectors (SSD) are crucial for fast neutron detection and spectroscopy in tokamaks due to their solid structure, neutron-gamma discrimination, and magnetic field resistance. They provide high energy resolutions without external conversion stages, enabling compact array installations in the harsh environment of a tokamak. Research comparing diamond and 4H-SiC detectors highlights thickness as a key efficiency factor. A 250 μm SiC epilayer with low doping, grown using a high-growth-rate process, exhibits sharp interfaces and minimal defects, essential for neutron detectors. The study evaluates detector designs, and performance using a 4H-SiC substrate. Various detector designs, such as Schottky diodes and p/n diodes, are assessed via I-V and C-V measurements, addressing high depletion voltage challenges. Preliminary neutron irradiation tests validate detector functionality, energy resolution and confirming detector reliability.

Enhancing the radiation hardness of vertical 4H–SiC detectors by the metal-oxide-semiconductor structure

In this work, 4H–SiC α-particle detectors with metal/semiconductor (MS) and metal/oxide/semiconductor (MOS) structures have been fabricated. The effects of introducing a SiO2 dielectric layer to form a MOS structure on the electrical properties, the performances, and the radiation hardness of the detectors have been evaluated systematically by comparing those with the MS structure. It is found that the reverse leakage current and the signal-to-noise ratio of α-particle detectors at high voltages can be improved by the MOS structure. Furthermore, the MOS structure exhibits much higher radiation hardness, as the energy resolution degradation of α particle detectors with MOS and MS structures after the γ irradiation is 0.59% and 2.87%, respectively. This work may provide a way to enhance the radiation hardness of 4H–SiC α-particle detectors.

Neutron irradiation and polarization effect of 4H–SiC Schottky detector

Neutron irradiation experiments were carried out on a 4H–SiC Schottky detector. The effects of neutron and accompanying γ-rays irradiation on the electrical properties, charge collection efficiency (CCE), energy resolution and crystal defects of 4H–SiC detectors were investigated. The total irradiation fluence was 1.24 × 1014 n/cm2, with an equivalent 1 MeV neutron fluence of 1.33 × 1015 n/cm2. Following neutron irradiation, the turn-on voltage increased significantly, and the capacitance of the Schottky junction no longer varied with the reverse bias voltage. The CCE of the detector decreased from 100% to 90.8%, while the energy resolution increased from 0.79% to 1.49%. The irradiated detector required a higher bias voltage for optimal performance. Additionally, we observed two defect levels, Ec-0.5 eV and Ec-0.35 eV, in the 4H–SiC crystals after irradiation. Their generation is also related to gamma ray irradiation. The detector exhibited a polarization effect, where the energy spectrum split into two distinct components during prolonged measurement of monoenergetic α particles. The peak position gradually shifted towards the lower energy side with increasing testing time. These effects can be mitigated by increasing the bias voltage to enhance the electric field strength in the drift region.

Performance of 4H–SiC radiation detector after high flux proton and Fe13+ heavy ion beam irradiation

A batch of Schottky diode 4H–SiC detectors was fabricated by using Ni/Au electrodes, which were irradiated by Fe13+ heavy ion beam current with a flux of 1 × 1013 n/cm2 to 4.35 × 1014 n/cm2 in a stepwise increment, the forward and reverse I–V characteristics before and after irradiation as well as the energy resolution of α particles produced by 241Am source were tested and compared. The test results show that the reverse leakage current of the 4H–SiC detector that we made after the radiation of Fe13+ heavy ion beam increases gradually with the increase of the irradiation flux, Schottky Barrier Height decreases continuously where the ideal factor gradually increases. When the flux is 4 × 1013 n/cm2, it has risen to 9 μA, but the detector still has an energy resolution of 2.63%. When the flux of Fe13+ heavy ion beam is increased to 8 × 1013 n/cm2, the very obvious degradation phenomenon appears, the Charge Collection Efficiency(CCE) is reduced from 100% to 66.08%, the energy resolution is changed from 1.6% to 4.33%. When flux is increased to 1.4 × 1014 n/cm2, and the detector's performance has degraded seriously, in which the energy resolution is decreased from 1.76% to 9.54%, meanwhile the CCE is reduced from 100% to 64.84%, but it can still be used. As the beam flux reaches 2 × 1014 n/cm2, the detector has been completely damaged. At the same time, the ability of the detector to be resist mixed ion beam irradiation was tested. The 4H–SiC detector still has an energy resolution of 2.51% after receiving a dose of irradiation, which concluded with 1 × 1017 n/cm2 protons and 2 × 1013 n/cm2 Fe13+ heavy ion beams.

Measurement of the neutron energy response curve of 4H-SiC detector based fission target detection system at the CSNS Back-n white neutron source

The fission target detection system, which is based on U-235(or U-238)fission target and large area 4H-SiC detector, has been developed for pulsed neutron detection. However, calibration of its neutron energy response curve is challenging due to its very low detection efficiency to fast neutrons. In the past, the calibration of the neutron sensitivity for the fission target detection system was limited to using ∼ 14 MeV neutrons generated by the Cockcroft-Walton accelerator. To obtain the response function for the complete range of neutron energies, extrapolation based on neutron fission cross sections was required. In this paper, we present the calibration of its energy response at the China Spallation Neutron Source (CSNS) Back-n beam line using the time of flight method, both with double-bunch and single-bunch mode in end-station 1(with a flight path of ∼ 55 m). The SiC detector with a thin sensitive thickness of 30 μm has lower scattering background than the traditional Si-PIN detector . As a result, the energy response curve of the fission target detection system above 0.26 MeV has been successfully acquired. The spectrum of the double-bunch mode was unfolded using the Bayesian algorithm, and the results indicate that, under conditions of sufficient counts, this method can yield results similar to those obtained from the single-bunch mode. The issue of pulse height defect of SiC detector to fission fragments is discussed. This experiment confirms that our detection system of SiC+fission target has a strong signal-to-noise ratio and anti-interference capability. At the same time, it demonstrates that this device has its own advantages in measuring the energy response of low sensitivity detectors.

Development of the large sensitive area 4H-SiC Schottky detectors at the Back-n

In this paper, we report a 4H-SiC Schottky type detector with a large sensitive area (10 × 10 mm 2 and 8 × 8 mm 2) and a high energy resolution (0.79%@−40V). The pulse-height spectra were measured with a244Cm α source, and the charge collection efficiency (CCE) can reach 100% higher than −50 V. The Back-n is a high luminosity white neutron beamline at the China Spallation Neutron Source (CSNS). We used the 4H-SiC detector array to measure the nuclear data at the Back-n. This marks the first application of the 4H-SiC detector at Back-n. We measured the 6Li (n, t) 4He reaction products at 0°. The performances of the detectors kept unchanged after 27 h irradiation with neutron beam. The products of17O (n, α) 14C reaction were also measured from different angles. The detector array can clearly identify the α events band of this reaction.

High-Resolution Alpha Spectrometry Using 4H-SiC Detectors: A Review of the State-of-the-Art

Silicon Carbide (SiC) semiconductor radiation detectors were first demonstrated in 1957, however, meaningful progress was delayed until the mid-1990s when high-quality epitaxially-grown SiC became available. Rapid progress ensued, and detection of alpha particles, gamma and X-rays, protons, fission fragments, heavy ions, beta particles, minimum-ionizing particles, and neutrons were all demonstrated. In the case of alpha-particle detection and spectrometry, the obtainable energy resolution is dependent on the design characteristics of the SiC detector as well as on the material and electronic properties of the SiC material. In this paper, we review the history of SiC alpha-particle detector development as well as the factors affecting detector performance and the prospects for further improvements. Detector design factors, including active-volume and entrance-window effects, are discussed in detail. Materials and electronic factors that influence the quality of alpha-particle detection are also discussed. These factors include SiC lattice defects, charge-carrier mobility, charge trapping, and the energy required to produce an electron-hole pair. Since the first demonstration of alpha-particle spectrometry, SiC detectors have evolved to the point that an energy resolution of 0.29% (15.9 keV FWHM for 5485.7-keV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">241</sup> Am alpha particles) has been reported. This resolution is comparable to the best obtainable with Silicon alpha-particle detectors. The prospects for further improvements in alpha spectrometry with SiC detectors are also discussed.

A study of the signal rising edge produced by a charge sensitive preamplifier connected to a 4H-SiC detector

In a general semiconductor detector system, the output amplitude of the charge-sensitive preamplifier (CSA) is proportional to the total charge induced by incident particles. The rising edge of the output signal provides information on the input current. The shape of the rising edge is not only affected by the carrier drifting but the discharge process of the equivalent capacitance (the detector capacitance and the capacitance caused by the detector package and the connecting cable, namely the stray capacitance) and the input resistance of the CSA. The equivalent capacitance and the input resistance often has a time constant of tens nanoseconds, which significantly affects the rising edge, particularly for fast detectors such as silicon carbide or diamond. This paper describes an α-particle testing system based on a Schottky 4H-SiC detector. The junction capacitance of the detector can be adjusted by changing the bias voltage, and the derivative waveforms of the CSA output are analyzed using an equivalent circuit. The results show that the falling edge of the derivative waveform corresponds to the discharge process of the equivalent capacitance and the input resistance in the circuit. The parameters of the detector capacitance, the stray capacitance and the input resistance can be obtained through fitting the decay time. The duration of the induced current of the detector can be measured from the rising edge of the derivative waveform. By comparing the theoretical and the measured value, the carrier mobility at different bias voltages can be derived.

Influence of heavy ion irradiation and high temperature on the performance of 4H–SiC Schottky barrier α particle detector

Traditional semiconductor detectors such as silicon and germanium are easily affected by ambient temperature and charge-particle ion's radiation. They can't work stably in harsh environments such as high temperature and strong radiation for a long time. In this paper, 4H-silicon carbide detectors based on a Schottky barrier diode (SBD) were fabricated and the combined influences of high temperatures and heavy ion irradiation on 4H–SiC detectors have been investigated. With no radiation, the 4H–SiC detectors have excellent I–V characteristics performance during a temperature range of 30–200 °C. Even at an ambient temperature of 200 °C, the leakage current of the 4H–SiC detector was only 107 nA at the full depletion voltage. Then 280 KeV C4+ heavy ions were used to irradiate the 4H-silicon carbide detectors, and the performances of the irradiated detectors were studied for different radiation doses from 1 × 1013 to 1 × 1016 ions/cm2 in a certain higher ambient temperature environment. For the fully depleted 4H-silicon carbide detectors in an ambient temperature of 140 °C, both the I–V characteristics and the energy resolution have shown a certain radiation damage at the radiation fluence of 1 × 1015 ions/cm2, while a significant deterioration was observed when the radiation fluence is up to 1 × 1016 ions/cm2. It means that the 4H–SiC detectors can withstand an irradiation dose of 1 × 1015 ions/cm2 at 140 °C. The time-dependent I–V curves were also investigated for the irradiated detectors for a standing time up to 192 h, and it's found that the irradiated detectors had minor changes in the leakage currents during a long time standing. A PN junction model with current and voltage equations was used to explain the phenomenon that the reverse leakage current increases with the increase of temperature. The surface recombination model was also used to explain the deterioration of I–V characteristics and energy resolution after irradiation.

Fabrication and characterization of high-resolution 4H-SiC epitaxial radiation detectors for challenging reactor dosimetry environments

Reactor dosimetry environments require radiation detectors that are capable of operating at high temperatures in extremely high neutron and gamma-ray dose rates. Silicon carbide (SiC) is one of the most promising wide bandgap semiconductors (3.27 eV) for harsh environment applications due to its radiation hardness, high breakdown voltage, high electron saturation velocity, and high thermal conductivity. In this paper, we summarize the prospect of Schottky barrier radiation detectors, fabricated on highly crystalline low-defect detector-grade n-type 4H-SiC epitaxial layers with thickness ranging from 20 to 250 lm, for harsh environment applications. A comprehensive discussion on the characterization of the parameters that influence the energy resolution has been included. The usage of electrical and radiation spectroscopic measurements for characterizing the junction and rectification properties, minority carrier diffusion lengths, and energy resolution has been elaborated. Characterization of crucial factors that limit the energy resolution of the detectors such as charge trap centers using thermally stimulated transient techniques is summarized. Finally, the effect of neutron fluence on the performance of the 4H-SiC detectors is discussed.

From a single silicon carbide detector to pixelated structure for radiation imaging camera

Abstract In this work, Schottky detectors based on a high-quality 4H-SiC epitaxial layer with a thickness of 50 µm were prepared. The Schottky contact of Ni/Au metallization with a 3 mm diameter was made. Reverse current-voltage characteristics were measured up to a voltage of 300 V with a leakage current of 40 pA at room temperature. Using an α-particle radiation source, the spectrometric characteristics of the 4H-SiC detector were tested. The best energy resolution in the FWHM (Full Width and Half Maximum) about 15 keV for 5.5 MeV α-particles was observed. Furthermore, a 4H-SiC pixel sensor (256 × 256) for the Timepix3 reading chip was prepared. The spectrometric and imaging properties of the new Timepix3 detector based on the 4H-SiC sensor were tested. The results showed high energy resolution and also high-quality X-ray imaging of the biological object.

Diagnostic of Fusion Neutrons on EAST Tokamak Using 4H-SiC Detector

Due to significant radiation hardness, thermal properties, low sensitivity to gamma rays, and fast response, the 4H-SiC detector exhibits promising properties in measuring the neutron production in the high-power fusion devices. To demonstrate the potential value of the 4H-SiC detectors as a neutron flux monitor and a neutron spectrometer on experimentally advanced superconducting tokamak (EAST) during the 2021 EAST deuterium–deuterium plasma experimental campaigns, the 4H-SiC detector covered with a 25- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thick <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> LiF film 95% enriched in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> Li and the 4H-SiC detector covered with a 1.5-mm-thick polyethylene layer were installed on a viewport located at the mid-plane of port F outside the EAST vacuum vessel and operated continuously during the whole experimental campaign with the goal to measure both the total and the time-dependent neutron emission from the plasma. The results are compared with those obtained with detectors routinely working at EAST ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">235</sup> U Fission Chambers). Despite their small active volumes, the 4H-SiC detectors were able to measure the total and the time-dependent neutron emission with good reliability and stability. The results of this work not only demonstrated the satisfactory performance of the 4H-SiC detector in the harsh environment of a mixed neutron–gamma high-radiation field and strong electromagnetic field, but also its applicability as a neutron spectrometer and a neutron flux monitor for fusion deuterium–plasma experiments.

Radiation Effects in Ultraviolet Sensitive Pd/4H-SiC Schottky Detectors

4H-SiC, by virtue of its intrinsic properties, is a very promising semiconductor material for fabricating rad-hard UV detectors suitable for harsh radiation environments. This paper aims to investigate the radiation tolerance of indigenously developed Pd/4H-SiC Schottky detectors, in order to determine their feasibility for space applications. 4H-SiC detectors of active area 1 × 1 mm2 were irradiated with electrons of energy 10 MeV at fluence of 2×1013 e-/cm2 and gamma rays from a Co-60 source with a total dose of 1 Mrad. The impact of these irradiations on electro-optical characteristics of the devices was studied by analyzing the changes in electrical parameters like reverse saturation current (Is), ideality factor (n), barrier height (ɸB), effective doping concentration (Neff) derived from I-V and C-V characteristics as well as in the UV spectral responsivity (i.e., from 248 to 365 nm) of the irradiated detectors. The electron irradiated device showed negligible change in I-V and C-V characteristics whereas its UV spectral responsivity at the peak wavelength of 290 nm reduced by 48.7 %. Gamma irradiated device displayed a noticeable variation in its electrical characteristics and 15.8 % reduction in the spectral responsivity (optical characteristics) at the peak wavelength. The results show that the radiation hardness of 4H-SiC detectors is better than that of conventional semiconductor ones, making it a more appealing choice as radiation detectors in space systems.

Performance of 4h-Sic Radiation Detector after High Flux Proton and Fe13+ Heavy Ion Beam Irradiation

Performance of 4h-Sic Radiation Detector after High Flux Proton and Fe13+ Heavy Ion Beam Irradiation

Timing Performance Simulation for 3D 4H-SiC Detector.

To meet the high radiation challenge for detectors in future high-energy physics, a novel 3D 4H-SiC detector was investigated. Three-dimensional 4H-SiC detectors could potentially operate in a harsh radiation and room-temperature environment because of its high thermal conductivity and high atomic displacement threshold energy. Its 3D structure, which decouples the thickness and the distance between electrodes, further improves the timing performance and the radiation hardness of the detector. We developed a simulation software—RASER (RAdiation SEmiconductoR)—to simulate the time resolution of planar and 3D 4H-SiC detectors with different parameters and structures, and the reliability of the software was verified by comparing the simulated and measured time-resolution results of the same detector. The rough time resolution of the 3D 4H-SiC detector was estimated, and the simulation parameters could be used as guideline to 3D 4H-SiC detector design and optimization.

Comparative study of Single Crystal (SC)-Diamond and 4H-SiC bulk radiation detectors for room temperature alpha spectroscopy

In this work, the fabrication, electrical characterization and alpha spectral characterization of single-crystal (SC) diamond bulk radiation detector have been carried out. The performance metrics of the SC-diamond bulk detector such as the leakage current density, charge collection efficiency, spectral resolution and polarization effects are studied and are compared with a bulk detector fabricated using High-Pure Semi-Insulating (HPSI) 4H-SiC. It is found that the SC-diamond detector exhibits lower leakage current density, higher μτ product, better spectral resolution and no polarization effects in comparison to the HPSI 4H-SiC detector. The time response analysis of the SC-diamond detector is carried out to study the effect of alpha particles on the operation of the SC-diamond detector. Accordingly, the stability of the SC-diamond detector is tested by evaluating the total counts versus real time and the performance of the diamond detector is found to be stable during the alpha-time spectroscopy. Hence, diamond bulk detectors using commercially available electronic grade diamond may be better suited for alpha particle spectroscopy compared to HPSI 4H-SiC of nearly equivalent thickness.

Systematic Analysis of Reliability of Large-Area 4H-SiC Charged Particle Detector Under Harsh He Ion Irradiation

Silicon carbide (SiC) detectors have great potential in nuclear fusion diagnosis and intense irradiation field measurement due to their outstanding irradiation resistance, high charge collection efficiency (CCE), and fast pulse response time. However, the irradiation resistance and the performance degradation of SiC detectors as a result of He ion irradiation remains unclear. In this article, SiC detectors based on 4H-type material with the p-i-n junction structure were prepared, and their I-V characteristics, α-particle spectra, and linearity of energy response were evaluated before and after He ion irradiation at fluences ranging from 1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> to 3 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . The preirradiated SiC detector exhibited low dark current (<; 1 nA), high CCE (98.5%), and good energy resolution (0.87%). At an He ion irradiation fluence of 1 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , detector performance degradation was negligible, with no increase of dark current, CCE decreased to 85%, and a 2.2% degradation of energy resolution. At a fluence of 3 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , CCE decreased to 19.3%, with an 8.57% degradation in energy resolution, but the dark current was still lower than 2 nA, with good spectra measurement capabilities and high linearity of energy response. These results indicate that the He ion irradiation resistance of 4H-SiC detectors is 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> times greater than silicon (Si) detectors.

Response of 4H-SiC Detectors to Ionizing Particles

We report the response of newly designed 4H-SiC Schottky barrier diode (SBD) detector prototype to alpha and gamma radiation. We studied detectors of three different active area sizes (1 × 1, 2 × 2 and 3 × 3 mm2), while all detectors had the same 4H-SiC epi-layer thickness of approximately µm, sufficient to stop alpha particles up to 6.8 MeV, which have been used in this study. The detector response to the various alpha emitters in the 3.27 MeV to 8.79 MeV energy range clearly demonstrates the excellent linear response to alpha emissions of the detectors with the increasing active area. The detector response in gamma radiation field of Co-60 and Cs-137 sources showed a linear response to air kerma and to different air kerma rates as well, up to 4.49 Gy/h. The detector response is not in saturation for the dose rates lower than 15.3 mGy/min and that its measuring range for gamma radiation with energies of 662 keV, 1.17 MeV and 1.33 MeV is from 0.5 mGy/h–917 mGy/h. No changes to electrical properties of pristine and tested 4H-SiC SBD detectors, supported by a negligible change in carbon vacancy defect density and no creation of other deep levels, demonstrates the radiation hardness of these 4H-SiC detectors.

IBIC analysis of SiC detectors developed for fusion applications

In this work, we consider a 4H-SiC detector as a plasma diagnostic system for the detection of fusion-born alpha particles in future nuclear fusion reactors. A nuclear microprobe was used to locally irradiate micrometer-sized regions of the detector with 3.5 MeV He ions to fluences from 5 × 109 to 5 × 1011 cm-2. Ion Beam Induced Charge (IBIC) microscopy was employed to study its degradation in Charge Collection Efficiency (CCE) and energy resolution after irradiation. At high reverse-bias voltages, both parameters remain practically unaffected for fluences up to 1 × 1011 cm-2, while a significant deterioration of the spectroscopic performance was observed above 3 × 1011 cm-2. A theoretical drift-diffusion model, in combination with Shockley-Read-Hall recombination statistics, was used to obtain the holes lifetime from the fitting of the experimental CCE values measured at different reverse voltages. Holes lifetime was found to strongly decrease with increasing particle fluence, changing from 57 ns in pristine detectors to 0.2 ns after irradiation with a fluence of 1 × 1011 cm-2.