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.

In this study the effects of proton irradiation and annealing on Low Gain Avalanche Detectors (LGADs) are investigated. Two LGADs and one p-in-n diode, produced by CNM (Centre Nacional de Microelectrònica 2018), were irradiated with 24GeV∕c-protons to a fluence of 1×1014neq∕cm2 and annealed at 60°C for up to 5000min. The sensors have an active area of 3×3mm2 and a thickness of 277μm. Current– and capacitance–voltage measurements, as well as laser measurements using the transient-current-technique were carried out to study the change of gain and the electric field after irradiation and consecutive annealing steps. The reduction of gain after irradiation is the main concern when using LGADs in high energy physics experiments. After annealing the sensors, no recovery of gain was observed. Different ways to measure the gain layer depletion voltage are discussed.

The upgrades of ATLAS and CMS for the High Luminosity LHC (HL-LHC) highlighted physics objects timing as a tool to resolve primary interactions within a bunch crossing. Since the expected pile-up is around 200, with an r.m.s. time spread of 180 ps, a time resolution of about 30 ps is needed. The timing detectors will experience a 1-MeV neutron equivalent fluence of about Phi(eq) = 10(14) and 10(15) cm(-2) for the barrel and end-cap regions, respectively. In this contribution, deep diffused Avalanche Photo Diodes (APDs) produced by Radiation Monitoring Devices are examined as candidate timing detectors for HL-LHC applications. To improve the detector's timing performance, the APDs are used to directly detect the traversing particles, without a radiator medium where light is produced. Devices with an active area of 8 x 8 mm(2) were characterized in beam tests. The timing performance and signal properties were measured as a function of position on the detector using a beam telescope and a microchannel plate photomultiplier (MCP-PMT). Devices with an active area of 2 x 2 mm(2) were used to determine the effects of radiation damage and characterized using a ps pulsed laser. These detectors were irradiated with neutrons up to Phi(eq) = 10(15) cm(-2) .

In view of the High Luminosity upgrade of the CERN Large Hadron Collider (HL-LHC), radiation tolerant silicon sensors are being developed in the framework of ATLAS, CMS, RD50 and other sensor R\&D projects. The HL-LHC beam parameters and hardware configuration should enable the collider to reach a peak instantaneous luminosity of $5\times10^{34}\textrm{ cm}^{-2}\textrm{s}^{-1}$, and an integrated luminosity of 250 fb$^{-1}/\textrm{year}$ with the goal of 3000 fb$^{-1}$ after about 12 years of operation. This will imply a factor 5 increase in instantaneous luminosity, and 10 in integrated luminosity with respect to the LHC. This increase in luminosity will also imply a factor 4 rise in the expected pile-up with respect to that observed during Run 2 of the LHC in ATLAS and CMS. Lastly, at the end of the operation period, radiation levels are expected to reach values above $1.6 \times 10^{16}$ fast hadrons/cm$^2$ at the innermost detectors. To cope with the increase in pile-up, silicon sensors with timing capabilities of the order of $\sim30$ ps are being developed. Given the expected radiation levels, the radiation-tolerance of these devices is of the utmost importance. In order to tackle these issues, one line of research investigates the possibility of producing radiation tolerant silicon sensors with intrinsic charge gain: Low Gain Avalanche Detectors (LGADs). The aim is to improve the signal height after irradiation as well as the timing capabilities of silicon sensors. Another approach is the use of 3D sensors. The implementation of 3D devices would resolve some of the issues arising from using LGADs such as gain-loss, radiation hardness at fluences beyond $10^{15}\textrm{ cm}^{-2}$, or a reduced fill factor. The aim of this paper is to give an overview of both technologies, their performance, and their current development status for timing applications.

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).

Recent interest in pile-up mitigation through fast timing at the HL-LHC has focused attention on technologies that now achieve minimum ionising particle (MIP) time resolution of 30 picoseconds or less. The constraints of technical maturity and radiation tolerance narrowed the options in this rapidly developing field for the ATLAS and CMS upgrades to low gain avalanche detectors and silicon photomultipliers. In a variety of applications where occupancies and doses are lower, devices with pixel elements of order 1 cm(2), nevertheless achieving 30 ps, would be attractive. In this paper, deep diffused Avalanche Photo Diodes (APDs) are examined as candidate timing detectors for HL-LHC applications. Devices with an active area of 8 x 8 mm(2) are characterised using a pulsed infrared laser and, in some cases, high energy particle beams. The timing performance as well as the uniformity of response are examined. The effects of radiation damage on current, signal amplitude, noise, and timing of the APDs are evaluated using detectors with an active area of 2 x 2 mm(2). These detectors were irradiated with neutrons up to a 1-MeV neutrons fluence Phi(epsilon q) = 10(15) cm(-2). Their timing performance was characterised using a pulsed infrared laser. While a time resolution of 27 +/- 1 ps was obtained in a beam test using an 8 x 8 mm(2) sensor, the present study only demonstrates that gain loss can be compensated by increased detector bias up to fluences of Phi(epsilon q) = 6.10(13) cm(-2). So it possibly falls short of the Phi(epsilon q) = 10(14) cm(-2) requirement for the CMS barrel over the lifetime of the HL-LHC.

Low gain avalanche detectors (LGADs), silicon sensors with intrinsic charge amplification, are being considered as a possible technology for tracking and timing in the high luminosity upgrade of the CERN Large Hadron Collider. In order to work in such an environment, LGADs must be sufficiently radiation hard. The characterisation before and after irradiation of properties, such as gain, charge collection, spatial homogeneity, space charge, and leakage current, is vital for assessing the performance and viability of LGADs. This paper presents the results obtained from the study of LGADs irradiated with 24-GeV/c protons up to a maximum fluence of 10(15) n(eq)/cm(2). The characterisation was performed mainly by means of the transient current technique with red and infrared laser pulses. It was found that the gain decreases with increasing fluence. At a fluence of 10(15) n(eq)/cm(2), the charge collected is similar to that of a normal p-i-n diode. Whilst this might be explained by an effective acceptor removal, it was also found that there are clear signs of a double junction in these devices, after irradiation. In addition, the spatial charge collection homogeneity before and after irradiation was evaluated.

For their operation at the CERN High Luminosity Large Hadron Collider (HL-LHC), the ATLAS and CMS experiments are planning to implement dedicated systems to measure the time of arrival of minimum ionizing particles with an accuracy of about 30 ps. The timing detectors will be subjected to radiation levels corresponding up to a 1-MeV neutrons fluence (Φeq) of 1015 cm−2 for the goal integrated luminosity of HL-LHC of 3000 fb−1. In this paper, deep-diffused Avalanche Photo Diodes (APDs) produced by Radiation Monitoring Devices are examined as candidate timing detectors for HL-LHC applications. These APDs are operated at 1.8 kV, resulting in a gain of up to 500. The timing performance of the detectors is evaluated using a pulsed laser. The effects of radiation damage on current, signal amplitude, noise, and timing performance of the APDs are evaluated using detectors irradiated with neutrons up to Φeq = 1015 cm−2.

This work focuses on the study of a set of Low Gain Avalanche Detectors (LGADs) produced by CNM, Barcelona (run 7859). Several samples were irradiated with 24-GeV/c protons up to different fluences, ranging between 10$^{12}$ and 10$^{15}$ n$_\textrm{eq}$/cm$^2$. This study concentrates mainly on the LGADs irradiated up to 10$^{14}$ n$_\textrm{eq}$/cm$^2$. The measurements performed to characterise the devices include TCT, edge-TCT, TPA-TCT, and CV/IV measurements. The main goals of these studies were to analyse the voltage required to fully deplete the multiplication layer of LGADs; to measure gain degradation; and to investigate the distribution of the electric field inside the devices after irradiation, as well as the characteristics of the space charge. In order to do so, the measurements were performed under different temperature, read-out and biasing conditions. The obtained data confirm that in highly proton-irradiated LGADs the depletion of the bulk starts from the back electrode, thus shifting the onset of charge multiplication towards higher voltages. This is caused by a space charge sign inversion that is in turn accompanied by the appearance of a triple junction. Furthermore, it was found that annealing causes a recovery of gain along with a reduction of the multiplication-onset voltage towards unirradiated-like values.

Silicon detectors with intrinsic charge amplification implementing a n++-p+-p structure are considered as a sensor technology for future tracking and timing applications in high energy physics experiments. The performance of the intrinsic gain in Low Gain Avalanche Detectors (LGAD) after irradiation is crucial for the characterization of radiation hardness and timing properties in this technology. LGAD devices irradiated with reactor neutrons or 800 MeV protons reaching fluences of 2.3 × 1016 neq/cm2 were characterized using Transient Current Technique (TCT) measurements with red and infra-red laser pulses. Leakage current variations observed in different production lots and within wafers were investigated using Thermally Stimulated Current (TSC). Results showed that the intrinsic charge amplification is reduced with increasing fluence up to 1015 neq/cm2 which is related to an effective acceptor removal. Further relevant issues were charge collection homogeneity across the detector surface and leakage current performance before and after irradiation.