Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance.

We present a novel design of fine segmented low gain avalanche diodes (LGAD) based on trenchisolation technique. The proposed design reduces the width of the no-gain inter-pad region down to less than 10 μm, from the 20-80 μm of the current LGAD technology, enabling the production of sensors with small pixel pitch and high fill-factor. Prototypes of this new technology were produced in the FBK laboratories. Their electrical characterization in terms of I-V, gain measurement and response to a focused laser, indicates that the trenches provide electrical isolation among pixels without any increase in the dark current level and without affecting the gain of the sensor. In addition, I-V measurements of p-i-n diodes with the same trench-isolation structure demonstrate that such termination scheme can withstand more than 500 Volts without reaching breakdown. This is well above the typical operating bias voltage of LGADs, thus confirming that trench-isolation is a promising solution for finely pixelated LGAD sensors.

The LEGEND Collaboration is searching for neutrinoless double-beta ( 0 ν β β ) decay by operating high-purity germanium detectors enriched in Ge 76 in a low-background liquid argon environment. Building on key technological innovations from the GERmanium Detector Array (GERDA) experiment and the MAJORANA DEMONSTRATOR experiment, LEGEND-200 has performed a first 0 ν β β decay search based on 61.0 kg yr of data. Over half of this exposure comes from our highest performing detectors, including newly developed inverted-coaxial detectors, and is characterized by an estimated background level of 0.5 − 0.2 + 0.3 cts / ( keV ton yr ) in the 0 ν β β decay signal region. A combined analysis of data from GERDA, the MAJORANA DEMONSTRATOR, and LEGEND-200, characterized by a 90% confidence level exclusion sensitivity of 2.8 × 10 26 yr on the half-life of 0 ν β β decay, reveals no evidence for a signal and sets a new observed lower limit at T 1 / 2 0 ν > 1.9 × 10 26 yr (90% confidence level). Assuming the decay is mediated by Majorana neutrinos, this corresponds to an upper limit on the effective Majorana mass in the range m β β < 75 – 200 meV , depending on the adopted nuclear matrix element.

Silicon photomultipliers (SiPMs) are arrays of many single-photon avalanche diodes (SPADs), all connected in parallel. Each SPAD is sensitive to a single photon. The SiPM output is proportional to the number of detected photons. These sensors are becoming more and more popular in different applications and they have been significantly improved over last years, decreasing the noise, increasing the cell fill-factor (FF) and thus achieving very high photon-detection efficiency (PDE). In FBK (Trento, Italy), we developed several different SiPM technologies and recently, pushing the fabrication process limits, we produced the new “ultra-high-density” (UHD) technology. This technology features deep-trenches between cells, for electrical and optical isolation, and is characterized by a very small cell pitch, from 12.5 μm down to 5 μm. Such very small cell dimensions pose several issues both in terms of design and fabrication of the SPADs. TCAD simulations have been used to redesign the cell structure, minimizing their border region. As an example, the SiPM with 5 μm cell-pitch has about 40000 SPADs per squared millimeter, thus a very high dynamic range. These very-small-cells SiPM have a lower correlated noise (including lower afterpulsing probability), faster recharge time and very good detection efficiency (despite the small SPAD dimension).