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
Journal Article
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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.
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.
Whilst the thermal management needs of future silicon detectors are increasing, the required mass and volume minimization of all detector ancillaries gets more demanding. This requires highly ...effective active cooling in very small channels. In the context of the AIDA-2020 project, a new test stand has been developed to characterize, with unprecedented level of accuracy, boiling flows of CO2 in mini- and micro-channels with hydraulic diameter ranging from 2 down to 0.1 mm. The heat transfer coefficient and pressure drop behaviour in stainless steel tubular evaporators for saturation temperatures from ＋20 to −25 °C, mass fluxes from 1200 to 100 kg m−2 s−1 and heat fluxes from 0.5 to 3.5 W/cm2 are discussed for one diameter. In addition, high speed camera observations of CO2 flow patterns recorded on micro-structured silicon cold plates are used to help with the interpretation of the heat transfer coefficient and pressure drop trends reported.
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
Journal Article
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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.
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.
Photocurrent amplification by gate effect in a three terminal carbon nanotube /n-Si photodetector.
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•Three terminal Carbon Nanotube/n-Si photodetectors.•Time response to nanosecond ...laser pulse.•Collecting photocharges by interdigitated electrodes.•Voltage doping in carbon nanotube/n-Si photodetectors.
We investigated the response of carbon nanotube/Si photodetectors to nanosecond light pulse using two electrode configurations for photovoltaic and photoconductive operations. When operating in photovoltaic mode, the devices show a linear dependence of the photocurrent as a function of the light pulse energy with rise time of 20 ns. In photoconductive mode, an increase of the maximum photocurrent as high as 30 times and a gain in the number of photogenerated charges up to 200% is recorded with a correspondent decrease in the time response below 10 ns. Current voltage characteristics measured as a function of the temperature indicate that the fast response of these devices can be ascribed to the formation of Schottky junctions at carbon nanotube/Si interface. These results make our devices comparable to most commercial photodetectors and pave the way for their use as avalanche photomultipliers.
Hybrid carbon nanotube-silicon (CNT–Si) junctions have been investigated by angle resolved photoemission spectroscopy (AR-XPS) with the aim to clarify the effects of a nonstoichiometric silicon oxide ...buried interface on the overall cell efficiency. A complex silicon oxide interface has been clearly identified and its origin and role in the heterojunction have been probed by exposing the cells to hydrofluoric (HF) and nitric (HNO3) acid. Real-time monitoring of the cell efficiencies during the steps following acid exposure (up to 1 week after etching) revealed a correlation between the thickness and chemical state of the oxide layer and the cell efficiencies. By matching the AR-XPS and Raman spectroscopy with the electrical response data it has been possible to discriminate the effects on the cell efficiency of the buried SiO x interface from those related to CNT acid doping. The overall cell behavior recorded for different thicknesses of the SiO x interface indicates that the buried oxide layer is likely acting as a passivating/inversion layer in a metal–insulator-semiconductor junction.
Abstract
At the visible light diagnostic (VLD) port at the Karlsruhe Research Accelerator (KARA), it is possible to study the energy spread of electron bunches by measuring the horizontal bunch ...profile of the incoherent synchrotron radiation. KALYPSO, an MHz-rate line-array detector, has been employed to measure the bunch profile. Recently, the KALYPSO system has been upgraded to a version of a microstrip sensor based on TI-LGAD. The measurements have shown that the system’s overall sensitivity was significant - at least by a factor of 20 improved, enabling the study of bunch profiles at low bunch charges. This contribution will present an overview of the upgraded setup and preliminary results.
Abstract Numerous plant extracts are abundant in biomolecules that can be employed in the biogenic synthesis of metallic nanoparticles owing to their potent reducing capabilities. The mechanism by ...which biomolecules act as reducers and expedite the reduction of silver ions remains poorly understood. This study presents an instantaneous and environmentally friendly synthesis of silver nanoparticles (AgNPs) using varying concentrations of commercially available green tea and concentrations of a dextrose-reducing solution. The AgNPs formed instantaneously, likely due to the competitive reaction between the polyphenols present in green tea and the dextrose. The best AgNPs produced using a diluted green tea solution at a concentration of 0.05 g of tea/ml and 100 μ l of dextrose solution exhibited high stability over a period of 90 days, as confirmed by UV–vis spectroscopy and dynamic light scattering. The results of antioxidant properties from diluited tea showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) 0.013 ± (0.1) μ mol Trolox Equivalent Anyioxidant Capacity (TEAC) TEAC/g, Ferric Reducing Antioxidant Power (FRAP) 10.3 ± (0.1) μ mol TEAC/g and Total Polyphenol Content (TPC) 0.12 ± (.001) μ gGAE(Galic Acid Equivalent)/g). The resulting nanoparticles are extremely small, measuring approximately 30 to 50 nm in size, and exhibit a spherical morphology as evidenced by SEM imaging. The plasmon bandwidth is better in more diluted tea and higher proportions of dextrose added than the others condition of synthesis. Probably, the results of 2nd extraction of green tea diluted can be evidence that phenolic compounds, mainly, caffeine and gallic acid, are contributing to forming and stabilizing the silver nanoparticles. This fundamental knowledge showed the method employed is ecologically sound and adheres to green principles.
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