We present a novel design of fine segmented low gain avalanchediodes ('GAD) based on trench-isolation 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 'GAD technology, enabling the production of sensors with small pixel pitch and high fill-factor. Prototypes of this new technologywere 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 'GADs, thus confirming that trench-isolation is a promising solution for finely pixelated 'GAD sensors.
Radiation resistant LGAD design Ferrero, M.; Arcidiacono, R.; Barozzi, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2019, Letnik:
919
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In this paper, we report on the radiation resistance of 50-micron thick Low Gain Avalanche Diodes (LGAD) manufactured at the Fondazione Bruno Kessler (FBK) employing different dopings in the gain ...layer. LGADs with a gain layer made of Boron, Boron low-diffusion, Gallium, Carbonated Boron and Carbonated Gallium have been designed and successfully produced at FBK. These sensors have been exposed to neutron fluences up to ϕn∼3⋅1016n∕cm2 and to proton fluences up to ϕp∼9⋅1015p∕cm2 to test their radiation resistance. The experimental results show that Gallium-doped LGAD are more heavily affected by the initial acceptor removal mechanism than those doped with Boron, while the addition of Carbon reduces this effect both for Gallium and Boron doping. The Boron low-diffusion gain layer shows a higher radiation resistance than that of standard Boron implant, indicating a dependence of the initial acceptor removal mechanism upon the implant density.
In this paper we present the numerical simulation of silicon detectors with internal gain as the main tool for 4-dimensional (4D) particle trackers design and optimization. The Low-Gain Avalanche ...Diode (LGAD) technology and its present limitations are reviewed with the aim of introducing the Resistive AC-Coupled Silicon Detectors (RSD) paradigm as a case study of our investigation. Authors here present Spice-like and 2D/3D Technological Computer-Aided Design (TCAD) simulations to characterize sensors in terms of both their electrostatic behavior, capacitive (dynamic) coupling and radiation-hardness performances, showing the methodological approach used in order to extract the set of layout rules allowing the release of RSD1, the incoming production run at Fondazione Bruno Kessler (FBK) of next-generation silicon detectors for 4D tracking with intrinsic 100% fill-factor.
First FBK production of 50 μm ultra-fast silicon detectors Sola, V.; Arcidiacono, R.; Boscardin, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
924
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Fondazione Bruno Kessler (FBK, Trento, Italy) has recently delivered its first 50 μm thick production of Ultra-Fast Silicon Detectors (UFSD), based on the Low-Gain Avalanche Diode design. These ...sensors use high resistivity Si-on-Si substrates, and have a variety of gain layer doping profiles and designs based on Boron, Gallium, Carbonated Boron and Carbonated Gallium to obtain a controlled multiplication mechanism. Such variety of gain layers will allow identifying the most radiation hard technology to be employed in the production of UFSD, to extend their radiation resistance beyond the current limit of ϕ∼ 1015 neq/cm2. In this paper, we present the characterisation, the timing performance, and the results on radiation damage tolerance of this new FBK production.
The High Energy Modular Ensemble of Satellites (HERMES) project is aimed to realize a modular X/gamma-ray monitor for transient events, to be placed on-board of a nano-satellite bus (e.g. CubeSat). ...This expandable platform will achieve a significant impact on Gamma Ray Burst (GRB) science and on the detection of Gravitational Wave (GW) electromagnetic counterparts: the recent LIGO/VIRGO discoveries demonstrated that the high-energy transient sky is still a field of extreme interest. The very complex temporal variability of GRBs (experimentally verified up to the millisecond scale) combined with the spatial and temporal coincidence between GWs and their electromagnetic counterparts suggest that upcoming instruments require sub-microsecond time resolution combined with a transient localization accuracy lower than a degree. The current phase of the ongoing HERMES project is focused on the realization of a technological pathfinder with a small network (3 units) of nano-satellites to be launched in mid 2020. We will show the potential and prospects for short and medium-term development of the project, demonstrating the disrupting possibilities for scientific investigations provided by the innovative concept of a new “modular astronomy” with nano-satellites (e.g. low developing costs, very short realization time). Finally, we will illustrate the characteristics of the HERMES Technological Pathfinder project, demonstrating how the scientific goals discussed are actually already reachable with the first nano-satellites of this constellation. The detector architecture will be described in detail, showing that the new generation of scintillators (e.g. GAGG:Ce) coupled with very performing Silicon Drift Detectors (SDD) and low noise Front-End-Electronics (FEE) are able to extend down to few keV the sensitivity band of the detector. The technical solutions for FEE, Back-End-Electronics (BEE) and Data Handling will be also described.
We present ARDESIA-16, an X-ray spectrometer based on a monolithic 16-element Silicon Drift Detector (SDD) matrix specifically designed for synchrotron applications. In this work, we describe the ...main design guidelines which we followed concerning the signal throughput, the energy efficiency, the energy resolution and the overall solid angle covered by detector elements. The characterization of the spectrometer has been made both with radioactive sources in a laboratory environment and with synchrotron light at the P06 beamline (DESY, Hamburg). Experimental results showed an average energy resolution at the optimum peaking time equal to 125 eV (FWHM at Mn Kα), a maximum achieved Output Count Rate (OCR) equal to 17 Mcps, an increase of the energy efficiency above 10 keV thanks to the 1 mm-thick SDD and an overall solid angle equal to 0.4 sr. Finally, we report the first X-ray fluorescence microscopy (XFM) images acquired with an ARDESIA spectrometer.
In this work we present the results of the experimental characterization of Silicon Drift Detectors (SDDs) readout by CUBE preamplifiers for X-ray spectroscopy measurements. One specific goal of the ...work was to characterize SDDs of different sizes cooled at low temperature in view of their use in the upgrade of the SIDDHARTA nuclear physics experiment. Beside the target application, the results of this work are also of interest for a more extended use of the SDDs in other X-ray spectroscopy applications. The SDDs have been designed as single units with square shape of different areas, 64 mm 2 (8 mm × 8 mm) and 144 mm 2 (12 mm × 12 mm), and also as monolithic array of 3×3 elements of the 8 mm × 8 mm unit (total area 26 mm × 26 mm). The read-out of the SDDs is based on a CMOS (Complementary Metal Oxide Semiconductor) preamplifier (CUBE) both for the single unit and for the 3×3 array. For the readout of the array, an Application Specific Integrated Circuit (ASIC) has been used. An energy resolution better than 124 eV at the Mn-Kα line has been measured with a 64 mm 2 SDD cooled at the temperature of 50 K. The energy resolution remains good (<;130 eV) also at short shaping time (250 ns) thanks to the noise feature of the CUBE preamplifier. Results of measurements on SDDs of different format and also on arrays of SDDs are presented in this work.
Silicon is still an interesting material for developing Concentration Photovoltaic (CPV) cells working at low and medium concentration range. In this work we describe modeling, design, fabrication ...technology and functional characterization of a small-area silicon solar cell suitable for CPV applications up to 200 suns. Two-dimensional (2-D) numerical simulations by a state-of-the-art Technology Computer Aided Design (TCAD) tool adopting calibrated physical models have been performed for both cell design and deep understanding of its performance. Specifically, the simulations have allowed the development and optimization of front contact grid scheme and design of the cell operating under medium concentration. The cell has been tested by means of a novel indoor concentrator system up to 300 suns and a conversion efficiency higher than 22% has been measured, according to numerical simulations. The dependence of short-circuit current on concentration factor has been observed to be super-linear. An excess of short-circuit current at 300 suns of approximately 8% has been measured. The super-linear effect has been investigated by means of numerical simulations and explained in terms of enhanced carrier diffusion length under concentrated light. The dependence of the super-linear effect on the incoming photon wavelength was also observed and discussed, showing that the super-linearity is due to the spectrum portion above 600nm only.
•22% efficient silicon concentrator solar cells have been realized.•We describe modeling, design, and fabrication technology.•Numerical simulations adopting calibrated physical models have been performed.•Numerical simulations have been exploited for cell design optimization.•A short-circuit current super-linear effect has been observed and discussed.
Abstract
The challenging demands of the ATLAS High Luminosity (HL-LHC) Upgrade aim for a complete swap of new generation sensors that should cope with the ultimate radiation hardness. FBK has been ...one of the prime foundries to develop and fabricate such radiation-hard 3D silicon (Si) sensors. These sensors are chosen to be deployed into the innermost layer of the ATLAS Inner Tracker (ITk). Recently, a pre-production batch of 3D Si sensors of 50 × 50 μm
2
pixel geometry, compatible with the full-size ITKPix (RD53B) readout chip, was fabricated. Two wafers holding temporary metal were diced at IZM, Germany, and a systematic QC test campaign was carried out at the University of Trento electronics laboratory. The paper briefly describes the 3D Si sensor design for ATLAS ITk and the required QC characterization setups. It comprises electrical tests (i.e., I-V, C-V, and I-T) of non-irradiated RD53B sensors. In addition, the study of several parametric analyses, i.e., oxide charge density, oxide thickness, inter-pixel resistance, inter-pixel capacitance, etc., are reported with the aid of Process Control Monitor (PCM) structures.
Abstract
We show the developments carried out to improve the silicon sensor technology for the detection of soft X-rays with hybrid X-ray detectors. An optimization of the entrance window technology ...is required to improve the quantum efficiency. The LGAD technology can be used to amplify the signal generated by the X-rays and to increase the signal-to-noise ratio, making single photon resolution in the soft X-ray energy range possible. In this paper, we report first results obtained from an LGAD sensor production with an optimized thin entrance window. Single photon detection of soft X-rays down to 452 eV has been demonstrated from measurements, with a signal-to-noise ratio better than 20.
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