Pixelated LGADs have been established as the baseline technology for timing detectors for the High Granularity Timing Detector (HGTD) and the Endcap Timing Layer (ETL) of the ATLAS and CMS experiments, respectively. The drawback of segmenting an LGAD is the non-gain area present between pixels and the consequent reduction in the fill factor. To overcome this issue, the inverse LGAD (iLGAD) technology has been proposed by IMB-CNM to enhance the fill factor and provide excellent tracking capabilities. In this work, we explore the use of iLGAD sensors for surface damage irradiation by developing a new generation of iLGADs, the periphery of which is optimized to improve the performance of irradiated sensors. The fabricated iLGAD sensors exhibit good electrical performances before and after X-ray irradiation.

The high-luminosity upgrade of the ATLAS and CMS experiments includes dedicated sub-detectors to perform the time-stamping of minimum ionizing particles (MIPs). These detectors will be exposed up to fluences in the range of 1.5-2.5 x 10(15) eta(eq)/cm(2) and require a time resolution per detecting layer of 30 ps, for non-irradiated sensors, to 50-70 ps (depending on the exposed fluences) for sensors at the end of their lifetime. To cope with these requirements, the low-gain avalanche diode (LGAD) has been chosen as the baseline detection technology. In this article, an in-depth radiation tolerance study on LGADs manufactured at IMB-CNM using a so-called shallow junction is presented. Proton irradiation at CERN-PS up to fluences of 3 x 10(15)eta(eq)/cm(2) and neutron irradiation at JSI-Ljubljana up to 2.5 x 10(15) eta(eq)/cm(2) were performed. Two different active thicknesses were studied: 35 mu m and 50 mu m. Gain degradation, operation stability, and timing performance were evaluated.

The high-luminosity upgrade of the ATLAS and CMS experiments includes dedicated sub-detectors to perform the time-stamping of minimum ionizing particles (MIPs). These detectors will be exposed up to fluences in the range of 1.5–2.5×1015neq/cm2 and require a time resolution per detecting layer of 30 ps, for non-irradiated sensors, to 50–70 ps (depending on the exposed fluences) for sensors at the end of their lifetime. To cope with these requirements, the low-gain avalanche diode (LGAD) has been chosen as the baseline detection technology. In this article, an in-depth radiation tolerance study on LGADs manufactured at IMB-CNM using a so-called shallow junction is presented. Proton irradiation at CERN-PS up to fluences of 3×1015neq/cm2 and neutron irradiation at JSI-Ljubljana up to 2.5×1015neq/cm2 were performed. Two different active thicknesses were studied: 35μm and 50μm. Gain degradation, operation stability, and timing performance were evaluated.

Silicon sensors are the go-to technology for high-precision sensors in particle physics. But only recently low-noise silicon sensors with internal amplification became available. The so-called Low Gain Avalanche Detector (LGAD) sensors have been developed for applications in High Energy Physics, but lack two characteristics needed for the measurement of low-energy protons (<60 keV): a thin entrance window (in the order of tens of nm) and the efficient amplification of signals created near the sensor's surface (in a depth below 1 um). In this paper we present the so-called proton Low Gain Avalanche Detector (pLGAD) sensor concept and some results from characterization of the first prototypes of the sensor. The pLGAD is specifically designed to detect low-energy protons, and other low-penetrating particles. It will have a higher detection efficiency than non-silicon technologies, and promises to be a lot cheaper and easier to operate than competing silicon technologies.

LGAD technology is established within the field of particle physics, as the baseline technology for the timing detectors of both the ATLAS and CMS upgrades at the HL-LHC. Pixelated LGADs have been proposed for the High Granularity Timing Detector (HGTD) and for the Endcap Timing Layer (ETL) of the ATLAS and CMS experiments, respectively. The drawback of segmenting an LGAD is the non-gain area between pixels and the consequent reduction in the fill factor. In this sense, inverse LGAD (iLGAD) technology has been proposed by IMB-CNM to enhance the fill factor and to reach excellent tracking capabilities. In this work, we explore the use of iLGAD sensors for X-Ray applications by developing a new generation of iLGADs. The periphery of the first iLGAD generation is optimized by means of TCAD tools, making them suitable for X-Ray irradiations thanks to the double side optimization. The fabricated iLGAD sensors exhibit good electrical performances before and after an X-Ray irradiation. The second iLGAD generation is able to withstand the same voltage, as contrary to the first iLGAD generation after irradiation.

In this contribution, we will present the status of the technological developments at IMB-CNM to fabricate Inverse Low Gain Avalanche Detectors (iLGAD) for pixelated detectors. This iLGAD sensor concept is one of the most promising technologies for enabling the future 4D tracking paradigm that requires both precise position and timing resolution. In the iLGAD concept, based on the LGAD technology, the readout is done at the ohmic contacts, allowing for a continuous unsegmented multiplication junction. This architecture provides a uniform gain over all the active sensor area. This concept was successfully demonstrated in a first generation of 300 μm thick iLGAD sensors. In the second generation, we have fabricated thick iLGAD sensor optimizing the periphery for X-Ray irradiations. Currently, we are developing a third generation based on 50 μm thick pixelated iLGADs optimized for timing detection, with a periphery design able to sustain high electric fields and a simpler single-side manufacturing process.

In this work, we present the pLGAD concept, which is based on the LGAD technology developed at IMB-CNM. We describe the main characteristics of this novel detector suitable for low energy particles detection. Using 2D TCAD numerical simulations we optimize its multiplication region characteristics, the V BD -Gain trade-off and the periphery design. Also, we define a first pLGAD fabrication run to integrate it at IMB-CNM clean room. Moreover, we describe the first n-type LGAD prototype.

Low Gain Avalanche Detector (LGAD) is the baseline sensing technology of the recently proposed Minimum Ionizing Particle (MIP) end-cap timing detectors (MTD) at the Atlas and CMS experiments. The current MTD sensor is designed as a multi-pad matrix detector delivering a poor position resolution, due to the relatively large pad area, around 1 mm(2); and a good timing resolution, around 20-30 ps. Besides, in his current technological incarnation, the timing resolution of the MTD LGAD sensors is severely degraded once the MIP particle hits the inter-pad region since the signal amplification is missing for this region. This limitation is named as the LGAD fill-factor problem. To overcome the fill factor problem and the poor position resolution of the MTD LGAD sensors, a p-in-p LGAD (iLGAD) was introduced. Contrary to the conventional LGAD, the iLGAD has a non-segmented deep p-well (the multiplication layer). Therefore, iLGADs should ideally present a constant gain value over all the sensitive region of the device without gain drops between the signal collecting electrodes; in other words, iLGADs should have a 100% fill-factor by design. In this paper, tracking and timing performance of the first iLGAD prototypes is presented.

LGAD detectors on 300 mu m thick high resistivity p-type substrates were proposed for the first time by IMB-CNM-CSIC. They are customized Avalanche Photodiodes (APD) to obtain a high electric field region confined close to the reversed junction. Therefore, only electrons generated by an incident particle passing through the detector and drifting to the n+ contact, start the impact ionization process. Thus, the collected charge is multiplied. The basic difference between APDs and LGADs is the gain. LGADs have a moderate gain in order to avoid the inherent problems due to high multiplication: cross talk and high noise. In that way, the detector signal can be kept high without increasing the noise. These devices have been successfully fabricated and extensively characterized, before and after irradiation. Unfortunately, neutron and proton radiation cause the degradation of the gain and the creation of bulk traps, degrading the timing resolution. One way to reduce the radiation induced degradation is to minimize the substrate thickness, thus improving the timing resolution of LGAD detectors. Two technology approaches have been contemplated: the use of SOI (Silicon on insulator) substrates and Silicon to Silicon bonding substrates, both with a very thin active silicon layer of 50 mu m. As a consequence, drifting distances of generated electrons and holes are significantly reduced, resulting in a decrease in the number of electrons and holes trapped by radiation induced bulk defects. A new family of thin detectors, produced in 2x2 arrays prototypes, for the ATLAS experiment High Granularity Timing Detector (HGTD) is proposed. These detectors are suitable for timing applications with time resolution in the range of 30 ps at 20 degrees C. Optimization of the LGAD structures for the HGTD experiment and the detector experimental performances are presented and discussed.

A silicon 3D detector with a single cell of 50 x 50 mu m(2) was produced and evaluated for timing applications. The measurements of time resolution were performed for Sr-90 electrons with dedicated electronics used also for determining time resolution of Low Gain Avalanche Detectors (LGADs). The measurements were compared to those with LGADs and also simulations. The studies showed that the dominant contribution to the timing resolution comes from the time walk originating from different induced current shapes for hits over the cell area. This contribution decreases with higher bias voltages, lower temperatures and smaller cell sizes. It is around 30 ps for a 3D detector of 50 x 50 mu m(2) cell at 150 V and -20 degrees C, which is comparable to the time walk due to Landau fluctuations in LGAD5. It even improves for inclined tracks and larger pads composed of multiple cells. A good agreement between measurements and simulations was obtained, thus validating the simulation results.

Low Gain Avalanche Detectors (LGAD) are based on a n(++)-p(+)-p-p(++) structure where an appropriate doping of the multiplication layer (p(+)) leads to high enough electric fields for impact ionization. Gain factors of few tens in charge significantly improve the resolution of timing measurements, particularly for thin detectors, where the timing performance was shown to be limited by Landau fluctuations. The main obstacle for their operation is the decrease of gain with irradiation, attributed to effective acceptor removal in the gain layer. Sets of thin sensors were produced by two different producers on different substrates, with different gain layer doping profiles and thicknesses (45, 50 and 80 mu m). Their performance in terms of gain/collected charge and leakage current was compared before and after irradiation with neutrons and pions up to the equivalent fluences of 5 . 10(15) cm(-2). Transient Current Technique and charge collection measurements with LHC speed electronics were employed to characterize the detectors. The thin LGAD sensors were shown to perform much better than sensors of standard thickness (similar to 300 mu m) and offer larger charge collection with respect to detectors without gain layer for fluences <2 . 10(15) cm(-2). Larger initial gain prolongs the beneficial performance of LGADs. Pions were found to be more damaging than neutrons at the same equivalent fluence, while no significant difference was found between different producers. At very high fluences and bias voltages the gain appears due to deep acceptors in the bulk, hence also in thin standard detectors.

In this paper we report measurements of the uniformity of time resolution, signal amplitude, and charged particle detection efficiency across the sensor surface of low-gain avalanche detectors (LGAD). Comparisons of the performance of sensors with different doping concentrations and different active thicknesses are presented, as well as their temperature dependence and radiation tolerance up to 6 x 10(14) n/cm(2). Results were obtained at the Fermilab test beam facility using 120 GeV proton beams, and a high precision pixel tracking detector. LGAD sensors manufactured by the Centro Nacional de Microelectronica (CNM) and Hamamatsu Photonics (HPK) were studied. The uniformity of the sensor response in pulse height before irradiation was found to have a 2% spread. The signal detection efficiency and timing resolution in the sensitive areas before irradiation were found to be 100% and 30-40 ps, respectively. A "no-response'' area between pads was measured to be about 130 mu m for CNM and 170 mu m for HPK sensors. After a neutron fluence of 6x10(14) n/cm(2) the CNM sensor exhibits a large gain variation of up to a factor of 2.5 when comparing metalized and non-metalized sensor areas. An irradiated CNM sensor achieved a time resolution of 30 ps for the metalized area and 40 ps for the non-metalized area, while a HPK sensor irradiated to the same fluence achieved a 30 ps time resolution.

In this work, the Infrared Lock-in Thermography (IR-LIT) is reported as a powerful tool for power devices diagnosis. They are monitored by thermal means after being biased in the frequency domain to activate and locate the weak spots responsible for their misbehaviour. As case studies, three different power devices are analysed: i) a Vertical Double Diffused MOS (VDMOS) presenting an elevated gate leakage current; ii) a SiC Schottky Barrier Diode with Tungsten contact (W-SBD) featuring a Schottky barrier modification by metal contact change; and iii) a Rad-Hard V-JFET with a lower breakdown voltage and a higher gate leakage current than expected.

For the high luminosity upgrade of the LHC at CERN, ATLAS is considering the addition of a High Granularity Timing Detector (HGTD) in front of the end cap and forward calorimeters at vertical bar z vertical bar = 3:5 m and covering the region 2:4 < vertical bar eta vertical bar < 4 to help reducing the effect of pile-up. The chosen sensors are arrays of 50 mu m thin Low Gain Avalanche Detectors (LGAD). This paper presents results on single LGAD sensors with a surface area of 1.3 x 1.3 mm(2) and arrays with 2 x 2 pads with a surface area of 2 x 2 mm(2) or 3 x 3 mm(2) each and different implant doses of the p(+) multiplication layer. They are obtained from data collected during a beam test campaign in autumn 2016 with a pion beam of 120 GeV energy at the CERN SPS. In addition to several quantities measured inclusively for each pad, the gain, efficiency and time resolution have been estimated as a function of the position of the incident particle inside the pad by using a beam telescope with a position resolution of few mu m. Different methods to measure the time resolution are compared, yielding consistent results. The sensors with a surface area of 1.3 x 1.3 mm(2) have a time resolution of about 40 ps for a gain of 20 and of about 27 ps for a gain of 50 and fulfil the HGTD requirements. Larger sensors have, as expected, a degraded time resolution. All sensors show very good efficiency and time resolution uniformity.

Low Gain Avalanche Detectors (LGADs) are based on a n(++)-p(+)-p-p(++) structure where appropriate doping of multiplication layer (p(+)) leads to high enough electric fields for impact ionization. Operation of these detectors in harsh radiation environments leads to decrease of gain attributed to the effective acceptor removal in the multiplication layer. In order to cope with that devices were produced where boron was replaced by gallium. The initial radiation hardness studies show a smaller degradation of gain with neutron fluence indicating that gallium is more difficult to displace/deactivate from the lattice site than boron.

A new vertical JFET transistor has been recently developed at the IMB-CNM, taking advantage of a deep-trenched 3D technology to achieve vertical conduction and low switch-off voltage. The silicon V-JFET transistors were mainly conceived to work as rad-hard protection switches for the renewed HV powering scheme (HV-MUX) of the ATLAS upgraded tracker. This work presents the features of the first batch of V-JFETs produced at the IMB-CNM clean room, together with the results of a full pre-irradiation characterization of the fabricated prototypes. Details of the technological process are provided and the outcome quality is also evaluated with the aid of reverse engineering techniques. Concerning the electrical performance of the prototypes, promising results were obtained, already meeting most of the HV-MUX specifications, both at room and below-zerotemperatures.

In this paper we report on the timing resolution obtained in a beam test with pions of 180 GeV/c momentum at CERN for the first production of 45 µm thick Ultra-Fast Silicon Detectors (UFSD). UFSD are based on the Low-Gain Avalanche Detector (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test had a pad area of 1.7 mm2. The gain was measured to vary between 5 and 70 depending on the sensor bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution was determined by doing Gaussian fits to the time-of-flight of the particles between one or more UFSD and the trigger counter. For a single UFSD the resolution was measured to be 34 ps for a bias voltage of 200 V, and 27 ps for a bias voltage of 230 V. For the combination of 3 UFSD the timing resolution was 20 ps for a bias voltage of 200 V, and 16 ps for a bias voltage of 230 V.

In this paper, an ASIC fabricated in 180 nm CMOS technology from AMS with the very front-end electronics used to readout LGAD sensors is presented as well as its experimental results. The front-end has the typical architecture for Si-strip readout, i.e., preamplification stage with a Charge Sensitive Amplifier (CSA) followed by a CR-RC shaper. Both amplifiers are based on a folded cascode structure with a PMOS input transistor and the shaper only uses passive elements for the feedback stage. The CSA has programmable gain and a configurable input stage in order to adapt to the different input capacitance of the LGAD sensors (pixelated, short and long strips) and to the different input signal (depending on the gain of the LGAD). The fabricated prototype has an area of 0.865 mm × 0.965 mm and includes the biasing circuit for the CSA and the shaper, 4 analog channels (CSA+shaper) and programmable charge injection circuits included for testing purposes. Noise and power analysis performed during simulation fixed the size of the input transistor to W/L = 860 μm/0.2 μm. The shaping time is fixed by design at 1 us and, in this ASIC version, the feedback elements of the shaper are passive, which means that the area of the shaper can be reduced using active elements in future versions. Finally, the different gains of the CSA have been selected to maintain an ENC below 400 electrons for a detector capacitor of 20 pF, with a power consumption of 150 μ W per channel.

An increasing demand for power electronic devices able to be operative in harsh radiation environments is now taking place. Specifically, in High Energy Physics experiments the required power devices are expected to withstand very high radiation levels which are normally too hard for most of the available commercial solutions. In this context, a new vertical junction field effect transistor (JFET) has been designed and fabricated at the Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica (IMB-CNM, CSIC). The new silicon V-JFET devices draw upon a deep-trenched technology to achieve volume conduction and low switch-off voltage, together with a moderately high voltage capability. The first batches of V-JFET prototypes have been already fabricated at the IMB-CNM clean room, and several aspects of their design, fabrication and the outcome of their characterization are summarized and discussed in this paper. Radiation hardness of the fabricated transistors have been tested both with gamma and neutron irradiations, and the results are also included in the contribution.

A new vertical JFET technology, based on a 3D trenched design, has been developed at the IMB-CNM. These transistors are conceived to work as rad-hard protection switches in the renewed High Voltage powering scheme for the Upgrade ATLAS ITk strip detectors. The first fabricated wafers have been fully characterized and the V-JFET performance is very close to the required specifications, showing excellent agreement with simulations. In this work the performance of the fabricated prototypes is tested under harsh ionizing radiation conditions. The variation of the main figures of merit is evaluated as a function of the Total Ionising Dose (TID) and the impact of different design parameters and fabrication strategies are compared. A final study, performed with the aid of TCAD simulations, is also included to understand the effects of the ionization damage observed on the V-JFET performance.