A new generation of 4H-SiC radiation detectors has demonstrated stable spectroscopic performance at temperatures up to 450°C, making this material a strong candidate for suprathermal alpha particle diagnostics in fusion environments such as ITER and DEMO. However, ion irradiation introduces defect-related trapping centers, including deep levels and defect clusters, which degrade charge transport and reduce charge collection efficiency, ultimately limiting detector performance under extreme conditions. This work investigates recovery mechanisms in an unmetallized 4H-SiC p-n junction detector irradiated with 3.5 MeV He++ ions at fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2 and irradiation temperatures between room temperature and 400°C, allowing assessment of damage evolution under different thermal conditions. The detector response was characterized by using ion beam induced charge at room temperature under controlled blue LED illumination at different intensities, enabling systematic evaluation of light-induced effects on charge transport. Results show that optical excitation induces a light-assisted increase in CCE, partially restoring spectroscopic response in heavily damaged regions, with the strongest effect observed at higher trap densities and increasing monotonically with illumination intensity. Comparison with a charge collection model provides additional insight into carrier dynamics in the presence of deep trapping centers, consistent with defects characterized by large capture cross sections and long carrier detrapping times. Overall, light-assisted trapping mitigation emerges as an effective mechanism to enhance detector stability and operational lifetime in harsh fusion-relevant environments. In parallel, dynamic annealing contributes to damage mitigation by reducing defect formation during irradiation rather than repairing pre-existing defects.

Ultrathin semiconductor photodiodes are of particular interest for beam monitoring and position detection in X‑ray synchrotron beamlines and particle‑therapy medical applications. For X‑ray beam position monitors (XBPMs) operating in transmission mode, and considering the absorption properties of silicon, device thicknesses must be kept below 10 μm to achieve transmission levels above 90% for typical photon energies around 10 keV. Although wide‑bandgap semiconductors such as diamond, and more recently even silicon carbide (SiC), offer notable advantages, silicon can remain as a cost‑effective and attractive option for some beam‑positioning and monitoring applications. In this work, single‑element and four‑quadrant photodiodes have been fabricated on ultrathin silicon layers with thicknesses of 5 μm and 3 μm using silicon‑on‑insulator (SOI) substrates. Additionally, 1–2 μm‑thick membrane devices have been produced through chemical back‑etching of high‑resistivity Float‑Zone (FZ) silicon wafers and they have been included as control structures to evaluate the limitations of processing in the absence of a buried oxide (BOX) etch‑stop layer. These devices have been characterized through physical and electrical measurements and they have been tested under X‑ray beam conditions at the BL13‑XALOC beamline of the ALBA Synchrotron. Particular attention has been devoted to assessing their position‑sensing capabilities, including two‑dimensional spatial uniformity and one‑dimensional spatial resolution, along with beam linearity, energy response, and X‑ray transmission characteristics. The devices fabricated on SOI substrates exhibit good functional detector performance, with the ones having a nominal thickness of 3 μm (corresponding to an effective active depth of approximately 2.75 m), representing, to our knowledge, the thinnest segmented transmissive silicon XBPMs reported to date.

In this work, we have investigated the performance of a 4H-SiC radiation sensor in the temperature range from 25 degrees C to 450 degrees C to explore its compatibility as detector of fast ion losses in plasma diagnostic of future nuclear fusion reactors. To simulate the escape of fusion-born alpha particles in D-T (deuterium-tritium) fusion plasmas, spectroscopic measurements were carried out in a vacuum chamber by irradiating the detector with a 3.5 MeV alpha beam from a Tandem accelerator. The detector was found to have an energy resolution <= 2% over the entire temperature range analyzed. Relevantly, the excellent spectrometric capabilities of the device have allowed us to calculate from experimental data, with unprecedented accuracy, the average energy required to create a single electron-hole pair in 4H-SiC as a function of temperature.

AbstractSilicon carbide (SiC) has outstanding physical properties therefore, diodes based on SiC are being considered for many radiation detection applications such as particle accelerator experiments and medical dosimetry. Moreover, by reducing the metal on the surface of the diode there is the potential to enhance its performance in some fields where the presence of metal is detrimental. To this end, SiC detectors with an epitaxially-grown graphene layer (EG), that substitutes the metallic contact, in the sensitive region were produced at IMB-CNM, profiting from the conductivity of the mono-atomic layer material. To isolate the effect of the graphene on the charge collection, samples without graphene were produced in parallel. In this paper, the effect of EG on Silicon Carbide p-in-n radiation detectors is studied in terms of charge collection with a radioactive source and by means of the transient current technique (TCT), which allows for position-dependent signal formation analysis. As a result of the former, we show the capability of the EG-SiC sensor for charge collection after signal integration, to a resolution close to that of a sensor fully metallised. Moreover, from the TCT studies, we observe uniform charge collection across the active region, as well as an up-to $$\sim $$ ∼ 40% transient amplitude damping which, compared with the $$\sim $$ ∼ 90% on the sample containing no metallic contact, proves that the presence of graphene benefits the performance of the device and that the technology is viable for radiation detection as an alternative to metal.

To cope with environments with high levels of radiation, non-silicon semiconductors such as silicon carbide detectors are being proposed for instrumentation. 4H-SiC diodes for radiation detection have been fabricated in the IMB-CNM Clean Room, for which different strategies to define the electrical contact of the implants had been implemented, in an attempt to optimise the technology for, e.g., medical applications or low energy radiation detection, as the material choice can affect the sensitivity of the device. Among these technologies, it is included an epitaxially-grown graphene layer as part of the electrical contact. In this paper, a selection of four configurations of the IMB-CNM SiC diodes are characterised in terms of radiation detector response. Photodiode performance under 20 keV X-rays irradiation in the XALOC beam line at ALBA Synchrotron is presented. Over-responses in the range of 12-19% linked to the interaction of the radiation with the metallic layers are observed. A good uniformity response as well as a good linearity at 0 V bias is reported, even in the under-depleted devices. This work exemplifies the good performance of SiC detectors fabricated at IMB-CNM specifically for low-energy X ray characterization at high X-ray intensities.

Ultrathin semiconductor photodiodes are of interest for beam position and monitoring in X-ray synchrotron beamlines and particle therapy medical applications. In this work, single and four-quadrant diodes have been fabricated on ultrathin Si films with thicknesses of 10 & mu;m, 5 & mu;m and 3 & mu;m from silicon on insulator (SOI) substrates. Physical and electrical characterization of the devices has been carried out. Good functional electrical characteristics have been obtained for the devices fabricated on the different silicon thicknesses. The impact of electron, neutron and proton irradiations on the electrical characteristics has been studied for the 10 & mu;m-thick devices. In spite of the observed diode leakage current increase and positive charge trapping in interquadrant isolation oxide, functional operation as radiation detector is verified upon illumination with a pulsed laser beam transient current technique.

Silicon carbide (SiC) is a wide bandgap semiconductor with outstanding properties that make it especially appropriate for radiation monitoring in radiation harsh environments and for elevated temperature operation. In this work, radiation effects in electron-, neutron-, and proton-irradiated 4H-SiC p-n junction diodes are investigated by means of electrical characterization, including current–voltage characteristics measured at different temperatures ranging from −50 °C to +200°C. Moreover, the stability of the radiation-induced effects is evaluated through a series of low-temperature treatments (up to 400 °C). Interestingly for applications, partial recovery of diode rectification functionality is observed for electron-irradiated devices. Furthermore, partial recuperation of detectors’ charge collection efficiency (CCE) is registered on either electron-, neutron-, or proton-irradiated devices. Remarkably, it is observed that the limited conduction registered for highly irradiated SiC detectors allows their operation in forward bias conditions. In fact, while providing some lower CCE, they show better energy resolution than in conventional reverse bias operation. Advantages of using SiC devices in alpha particle detection in harsh environments, as well as simplification of current Si experiments, can be envisaged.

The unique electrical and material properties of 4H-silicon-carbide (4H-SiC) make it a promising candidate material for high rate particle detectors. In contrast to the ubiquitously used silicon (Si), 4H-SiC offers a higher carrier saturation velocity and larger breakdown voltage, enabling a high intrinsic time resolution and mitigating pile-up effects. Additionally, as radia-tion hardness requirements grow more demanding in the context of future high luminosity high energy physics experiments, wide-bandgap materials such as 4H-SiC could offer better perfor-mance due to low dark currents and higher atomic displacement thresholds. In this work, the detector performance of 50 mu m thick 4H-SiC p-in-n planar pad sensors was investigated at room temperature, using an 241Am alpha source at reverse biases of up to 1100 V. Samples subjected to neutron irradiation with fluences of up to 1 x 1016 neq/cm2 were included in the study in order to quantify the radiation hardness properties of 4H-SiC. A calibration of the absolute number of collected charges was performed using a GATE simulation. The obtained results are compared to previously performed UV transient current technique (TCT) studies. Samples exhibit a drop in charge collection efficiency (CCE) with increasing irradiation fluence, partially compensated at high reverse bias voltages far above full depletion voltage. At fluences of 5 x 1014 neq/cm2 and 1 x 1015 neq/cm2, CCEs of 64 % and 51 % are obtained, decreasing to 15 % at 5 x 1015 neq/cm2. A plateau of the collected charges is observed in accordance with the depletion of the volume the alpha particles penetrate for an unirradiated reference detector. For the neutron-irradiated samples, such a plateau only becomes apparent at higher reverse bias, roughly 600 V and 900 V for neutron fluences of 5 x 1014 neq/cm2 and 1 x 1015 neq/cm2. For the highest investigated fluence, CCE behaves almost linearly with increasing reverse bias. Compared to UV-TCT measurements, the reverse bias required to deplete a sensitive volume covering full energy deposition is lower, due to the small penetration depth of the alpha particles. At the highest reverse bias, the measured CCE values agree well with earlier UV-TCT studies, with discrepancies between 1% and 5%.

Due to their low leakage current, low noise levels, high thermal conductivity, and potential radiation hardness, SiC devices offer various advantages over Si devices in certain applications. As a result, they are being considered for operation in harsh environments, such as plasma diagnostic systems in future nuclear fusion reactors or in high energy physics applications. We report on relevant results of the GRACE project, which seeks to deliver a new generation of SiC sensors with graphene-enhanced contacts. Such devices are aimed to be radiation-hard and functional at high temperatures. The work presented in this paper focuses on the optimisation of the electrical contacts, along with the electrical characterisation and radiation-tolerance assessment of the first sensor prototypes produced.

This article explores the viability of nitrogen enriched silicon for particle physics application. For that purpose silicon diodes and strip sensors were produced using high resistivity float zone silicon, diffusion oxygenated float zone silicon, nitrogen enriched float zone silicon and magnetic Czochralski silicon. The article features comparative studies using secondary ion mass spectrometry, electrical characterization, edge transient current technique, source and thermally stimulated current spectroscopy measurements on sensors that were irradiated up to a fluence of 10 15 n eq /cm 2 . Irradiations were performed with 23 MeV protons at the facilities in Karlsruhe (KIT), with 24 GeV/c protons at CERN (PS-IRRAD) and neutrons at the research reactor in Ljubljana. Secondary ion mass spectrometry measurements give evidence for nitrogen loss after processing, which makes gaining from nitrogen enrichment difficult.

Owing to their low dark current, high transparency, high thermal conductivity, and potential radiation hardness, there is a special interest in silicon carbide (SiC) devices for radiation monitoring in radiation harsh environments and with elevated temperatures and, especially, for the plasma diagnostic systems in future nuclear fusion reactors. In this work, four-quadrant p-n junction diodes produced on epitaxial 4H-SiC substrates are studied. The impact of electron, neutron, and proton irradiations (up to fluences of 1 × 10 16 electrons (e)/cm 2 , 2 × 10 15 neutrons (n)/cm 2 , and 2.5 × 10 15 protons (p)/cm 2 , respectively) on the electrical characteristics is studied by means of current-voltage (I-V) and capacitance-voltage (C-V) techniques. Regardless of the particle type and applied fluences, the results show similar low reverse currents for irradiated SiC devices, which are at least about four orders of magnitude lower than comparable Si devices. The effects of irradiation on interquadrant resistance and charge build-up in the interquadrant isolation are assessed. Furthermore, device performance as a radiation detector is investigated upon exposure to a collimated 239 Pu- 241 Am- 244 Cm trialpha source. The performance at room temperature is preserved even for the highest irradiation fluences, despite the fact that the rectification character in electrical characteristics is lost. From the results, advantages of using SiC devices in alpha particle detection in harsh environments can be envisaged.

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 x 10(9) to 5 x 10(11) 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 1x10(11) cm(-2), while a significant deterioration of the spectroscopic performance was observed above 3 x 10(11) 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 x 10(11) cm(-2).

Silicon photodiodes are very useful devices as X-ray beam monitors in synchrotron radiation beamlines, as well as other astronomy and space applications. Owing to their lower susceptibility to variable temperature and illumination conditions, there is also special interest in silicon carbide devices for some of these applications. Moreover, radiation hardness of the involved technologies is a major concern for high-energy physics and space applications. This work presents four-quadrant photodiodes produced on ultrathin (10 mu m) and bulk Si, as well as on SiC epilayer substrates. An extensive electrical characterization has been carried out by using current-voltage (I-V) and capacitance-voltage (C-V) techniques. The impact of different temperature (from -50 degrees C to 175 degrees C) and visible light conditions on the electrical characteristics of the devices has been evaluated. Radiation effects caused by 2 MeV electron irradiation up to 1 x 10(14), 1 x 10(15) and 1 x 10(16) e/cm(2) fluences have been studied. Special attention has been devoted to the study of charge build-up in diode interquadrant isolation, as well as its impact on interquadrant resistance. The study of these electrical properties and its radiation-induced degradation should be taken into account for device applications.

An alternative gate oxide configuration is proposed to enhance the SiO2/SiC interface quality, enabling high mobility 4H-SiC lateral metal-oxide-semiconductor field-effect transistors (MOSFETs). The gate oxide is prepared by the combination of rapid thermal oxidation in N2O ambient, boron diffusion into SiO2, and plasma enhanced chemical vapor deposition of tetraethyl orthosilicate oxide. Capacitance-voltage (C-V) and conductance-voltage (G-V) measurements on fabricated capacitors reveal a reduction of both interface trap and near interface oxide trap densities. The fabrication of MOSFETs with very high field-effect mobility (μfe) values, up to 160 cm2/V s, is enabled. Several channel orientations, with respect to the wafer flat {112¯0}, have been studied to check μfe values and isotropy. Higher μfe values are obtained for a channel orientation of 90°. Boron distribution is studied by secondary ion mass spectrometry (SIMS) and time of flight SIMS. We propose that the combination of boron and nitrogen induces changes in the structure of the gate oxide which are positive in terms of the SiO2/SiC interface quality.

Silicon photodiodes are very useful devices as X-ray beam monitors in synchrotron radiation beamlines. Owing to Si absorption, devices thinner than 10 μ m are needed to achieve transmission over 90% for energies above 10 keV . In this work, new segmented four-quadrant diodes for beam alignment purposes are fabricated on both ultrathin (10 μ m-thick) and bulk silicon substrates. Four-quadrant diodes implementing different design parameters as well as auxiliary test structures (single diodes and MOS capacitors) are studied. An extensive electrical characterization, including current-voltage (I-V) and capacitance-voltage (C-V) techniques, is carried out on non-irradiated and gamma-irradiated devices up to 100 Mrad doses. Special attention is devoted to the study of radiation-induced charge build-up in diode interquadrant isolation dielectric, as well as its impact on device interquadrant resistance. Finally, the devices have been characterized with an 8 keV laboratory X-ray source at 108 ph/s and in BL13-XALOC ALBA Synchroton beamline with 1011 ph/s and energies from 6 to 16 keV . Sensitivity, spatial resolution and uniformity of the devices have been evaluated.

The radiation hardness and thermal stability of the electrical characteristics of atomic layer deposited Al2O3 layers to be used as passivation films for silicon radiation detectors with slim edges are investigated. To directly measure the interface charge and to evaluate its change with the ionizing dose, metal-oxide-silicon (MOS) capacitors implementing differently processed Al2O3 layers were fabricated on p-type silicon substrates. Qualitatively similar results are obtained for degradation of capacitance-voltage and current-voltage characteristics under gamma and proton irradiations up to equivalent doses of 30 Mrad and 21.07 Mrad, respectively. While similar negative charge densities are initially extracted for all non-irradiated capacitors, superior radiation hardness is obtained for MOS structures with alumina layers grown with H2O instead of O-3 as oxidant precursor. Competing effects between radiation-induced positive charge trapping and hydrogen release from the H2O-grown Al2O3 layers may explain their higher radiation resistance. Finally, irradiated and non-irradiated MOS capacitors with differently processed Al2O3 layers have been subjected to thermal treatments in air at temperatures ranging between 100 degrees C and 200 degrees C and the thermal stability of their electrical characteristics has been evaluated. Partial recovery of the gamma-induced degradation has been noticed for O-3-grown MOS structures. This can be explained by a trapped holes emission process, for which an activation energy of 1.38 +/- 0.15 eV has been extracted. (C) 2015 Elsevier Ltd. All rights reserved.

The effects of 2 MeV electron irradiation on the electrical properties of high-k dielectric based metal–insulator–semiconductor capacitors have been studied. Samples consist of 5.9 nm-thick films of aluminum oxide and hafnium oxide deposited by atomic layer deposition on silicon substrates. Deep-level transient spectroscopy (DLTS) and admittance measurements reveal that electron irradiation modifies the defect density of both surface states at the dielectric–semiconductor interface and border traps existing inside the dielectric. The experimental results indicate that irradiation has a double effect. The incident electrons transfer their energy and generate additional surface states, leading to a degradation of the interface. On the other hand, irradiation generates electron–hole pairs inside the dielectric. Some of the holes are trapped by border traps located inside the dielectric at locations close to the interface. As a result, border traps capturing holes are neutralized and become inactive after irradiation. Moreover, interface state profiles, as measured by DLTS, are affected by the presence of border traps and yield overestimated interface state densities. Admittance spectroscopy is used to distinguish among border traps and interface traps. A detailed study of the conductance signal as a function of voltage, temperature and frequency for samples with different irradiation doses (nonirradiated, 2.5, 25, and 250 Mrad) is presented here. The influence of the irradiation dose has been analyzed in order to compare the defect distribution before and after irradiation.

In this work, a charge pumping characterization has been carried out on 4H-SiC nMOSFETs built with different SiC doping processes. Because charge pumping (CP) measurements on SiC are complex to implement, three different CP methods have been used for Dit characterization. The impact of geometrical and electrical parameters on each method is studied. Finally, it is detailed the full measurement flow chosen for a deeper and more accurate understanding of Dit electrical characterization.