Search

This paper covers the main technological and design aspects relevant to the development of a new generation of thin 3D pixel sensors with small pixel size aimed at the High-Luminosity LHC upgrades., 2 pages, 3 figures, 2015 Pisa Meeting

Radiation hardness of planar detectors processed from pre-irradiated and thermo-annealed n-type FZ silicon substrates, and standard FZ as a reference, was studied. The high purity n-Si wafers with carrier concentration 4.8×10 11 cm −3 were pre-irradiated in Kiev's nuclear research reactor by fast neutrons to fluence of about 10 16 neutrons/cm 2 and thermo-annealed at a temperature of about 850 °C. Silicon diodes were fabricated from standard and pre-irradiated silicon substrates by IRST (Italy). All diodes were subsequently irradiated by fast neutrons at Kiev and Ljubljana nuclear reactors. The dependence of the effective doping concentration as a function of fluence ( N eff =f ( Φ )) was measured for reference and pre-irradiated diodes. Pre-irradiation of silicon improves the radiation hardness by decreasing the acceptor introduction rate ( β ), thus mitigating the depletion voltage ( V dep ) increase. In particular, β in reference samples is about 0.017 cm −1 , and for pre-irradiated samples is about 0.008 cm −1 . Therefore, the method of preliminary irradiation can be useful to increase the radiation hardness of silicon devices to be used as sensors or detectors in harsh radiation environments.

Silicon (Si) photodiodes with a finger p–n junction have been modeled, designed, fabricated and tested. The surface depletion region (down to 200 nm from top of the Si substrate) between neighboring n+-finger implants provides for a very effective collection of photons in the blue spectral range, thus enhancing the responsivity, especially for devices with larger interfinger distance. At 420 nm wavelength and 5 V reverse bias the measured responsivity is 0.24 A/W with respect to 0.14 A/W standard reference photodiodes made on the same substrate, with a maximum value of 0.44 A/W observed at 20 V reverse bias. The finger photodiodes have been evaporated by metalloporphyrin films, able to change their absorption spectrum in the Soret band, around 440 nm, on exposure to volatile organic compounds (VOCs). A blue light source has been employed to test the sensors response to ethanol at room temperature and concentrations down to 300 ppm were measured with the Zn-T(heptyloxy)PP.

Silicon 3D detectors consist of an array of columnar electrodes of both doping types which penetrate entirely in the detector bulk, perpendicularly to the surface. They are emerging as one of the most promising technologies for innermost layers of tracking devices for the foreseen upgrades of the LHC. Until recently, properties of 3D sensors have been investigated mostly with ATLAS readout electronics. 3D pixel sensors compatible with the CMS readout were first fabricated at SINTEF (Oslo, Norway), and more recently at FBK (Trento, Italy) and CNM (Barcelona, Spain). Several sensors with different electrode configurations, bump-bonded with the CMS pixel PSI46 readout chip, were characterized in laboratory and tested at Fermilab with a proton beam of 120 GeV/c. Preliminary results of the data analysis are presented. © 2012 CERN. Published by Elsevier B.V. All rights reserved.

We report on the functional characterization of planar sensors with active edges fabricated at Fondazione Bruno Kessler (FBK), Trento, Italy. The measurements here reported were performed by means of laser and X-ray beam scans mainly focusing on the signal efficiency of the edge region of the devices. Results are very encouraging and show very good sensitivity up to few microns away from the device physical edge.

The results discussed in this paper are relevant to junction field effect transistors (JFETs) and JFET-based charge sensitive amplifiers fabricated in a detector compatible process. Such structures were irradiated with 27 MeV protons to evaluate the suitability of the technology for space applications and high-energy physics experiments from the standpoint of radiation tolerance. The process investigated in this work, originally designed for the fabrication of silicon detectors to be operated in a fully depleted condition, has been tuned to embed N-channel JFETs, NMOS devices and bipolar transistors in the same high resistivity substrate. The most significant electrical parameters have been monitored after exposing the test structures to different proton fluences in order to characterize their total dose and bulk damage response. Comparison with the results from previous irradiations with /spl gamma/-rays might be helpful in shedding light on the fundamental mechanisms underlying radiation damage in JFET silicon devices.

The high luminosity SuperB asymmetric e + e − collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10 36 cm −2 s −1 with moderate beam currents and a reduced center of mass boost with respect to earlier B-Factories. An improved vertex resolution is required for precise time-dependent measurements and the SuperB Silicon Vertex Tracker will be equipped with an innermost layer of small radius (about 1.5 cm), resolution of 10 – 15 μ m in both coordinates, low material budget ( 1 % X0), and able to withstand a background rate of several tens of MHz/cm 2 . The ambitious goal of designing a thin pixel device with these stringent requirements is being pursued with specific R&D programs on different technologies: hybrid pixels, CMOS MAPS and pixel sensors developed with vertical integration technology. The latest results on the various pixel options for the SuperB SVT will be presented.

We report on further developments of our proposed design approach for a full in-pixel signal processing chain of deep N-well monolithic active pixel sensor, by exploiting the triple well option of a CMOS 130 nm process. Two different geometries of the collecting electrode (namely "Apsel 3T(1) M(1)" and "Apsel 3T(1) M(2)") was implemented to compare their charge collection efficiency. The results of the characterization of the various versions of pixel matrices with a pion beam of 120 GeV/c at the SPS H6 CERN facility will be presented. The performances of an "Apsel 3T(1)" chip irradiated with a dose up to 10 Mrad (Co(60)) was also measured. Comparison will be presented among the irradiated and the new chip showing the impact of radiation damages on tracking efficiencies. (C) 2010 Elsevier B.V. All rights reserved. RI Forti, Francesco/H-3035-2011; Neri, Nicola/G-3991-2012; Gabrielli, Alessandro/H-4931-2012; Villa, Mauro/C-9883-2009; Dalla Betta, Gian-Franco/I-1783-2012; Ratti, Lodovico/I-8836-2012; Giorgi, Filippo Maria/I-7602-2012

This paper presents the experimental results relevant to JFET charge preamplifiers fabricated in a detector-compatible technology. This fabrication process, developed at the Istituto per la Ricerca Scientifica e Tecnologica (ITC-IRST), Trento, Italy, is being tuned with the aim of integrating a multichannel mixed analog-digital circuit together with semiconductor detectors in a high-resistivity substrate. Possible applications are in the field of medical and industrial imaging, in space and high energy physics experiments. An all-NJFET charge sensitive amplifier, which can use either a resistive or a nonresistive reset in the feedback network, has been tested. The two configurations have been studied, paying particular attention to noise performances, in view of the design of the complete readout channel.

To investigate the radiation hardness of standard and oxygen enriched silicon devices with respect to high energy electrons (900 MeV ) , an irradiation experiment has been performed at Elettra, the synchrotron facility in Trieste (Italy). No significant differences have been observed in the electrical parameters of oxygenated and standard structures after the irradiation up to a fluence of about 4.5×10 14 cm −2 for what concerns the full depletion voltage variations and the increase of the reverse leakage current. Only the reverse annealing of the full depletion voltage appears to benefit somewhat from the oxygenation of silicon substrate. These results seem to indicate that for irradiation with high energy electrons there is no clear advantage in using oxygen enriched silicon wafers up to very high fluence values.

We present some results obtained with silicon and gallium arsenide pixel detectors to be applied in the field of digital mammography. Even though GaAs is suitable for medical imaging applications thanks to its atomic number, which allows a very good detection efficiency, it often contains an high concentrations of traps which decrease the charge collection efficiency (CCE). So we have analysed both electrical and spectroscopic performance of different SI GaAs diodes as a function of concentrations of dopants in the substrate, in order to find a material by which we can obtain a CCE allowing the detection of all the photons that interact in the detector. Nevertheless to be able to detect low contrast details, efficiency and CCE are not the only parameters to be optimized; also the stability of the detection system is fundamental. In the past we have worked with Si pixel detectors; even if its atomic number does not allow a good detection efficiency at standard thickness, it has a very high stability. So keeping in mind the need to increase the Silicon detection efficiency we performed simulations to study the behaviour of the electrical potential in order to find a geometry to avoid the risk of electrical breakdown.

Owing to their superior radiation hardness compared to planar detectors, 3D detectors are one of the most promising technologies for the LHC upgrade foreseen in 2017. Fondazione Bruno Kessler has developed 3D Double-side Double-Type Column (3D-DDTC) detectors providing a technological simplifications with respect to a standard 3D process while aiming at comparable detector performance. We present selected results from the electrical characterization of 3D-DDTC structures from the second batch made on p-type substrates, supported also by TCAD simulations.

The SUPERB asymmetric e(+)e(-) collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10(36) cm(-2) s(-1) with moderate beam currents, allowing precision measurements in the flavour sector sensitive to New Physics. The conceptual design of the Silicon Vertex Tracker for the SUPERB Detector is presented, based on double-sided silicon strip detectors for the outer layers, with the addition of an innermost Layer 0 close to the interaction point, with low material budget and capable of sustaining a background rate of several MHz/cm(2). (C) 2010 Elsevier B.V. All rights reserved.

The aim of this work is to present the main technological developments carried out at FBK for micro machined radiation sensors used in High Energy Physics (HEP) experiments. We report on the main technological issues to integrate silicon etching (wet and dry) techniques in the fabrication flow for silicon detector and we show some examples of innovative detectors realized by means of these technologies

Silicon radiation sensors fabricated with micromachining technologies offer a number of advantages compared to their planar counterparts, making them appealing for an increasing number of applications. This paper provides an overview of the most interesting developments in this field by Fondazione Bruno Kessler in collaboration with the University of Trento.

The PixFEL project aims to develop an advanced X-ray camera for imaging suited for the demanding requirements of next generation free electron laser (FEL) facilities. New technologies can be deployed to boost the performance of imaging detectors as well as future pixel devices for tracking. In the first phase of the PixFEL project, approved by the INFN, the focus will be on the development of the microelectronic building blocks, carried out with a 65 nm CMOS technology, implementing a low noise analog front-end channel with high dynamic range and compression features, a low power ADC and high density memory. At the same time PixFEL will investigate and implement some of the enabling technologies to assembly a seamless large area X-ray camera composed by a matrix of multilayer four-side buttable tiles. A pixel matrix with active edge will be developed to minimize the dead area of the sensor layer. Vertical interconnection of two CMOS tiers will be explored to build a four-side buttable readout chip with small pixel pitch and all the on-board required functionalities. The ambitious target requirements of the new pixel device are: single photon resolution, 1 to 104 photons @ 1 keV to 10 keV input dynamic range, 10-bit analog to digital conversion up to 5 MHz, 1 kevent in-pixel memory and 100 μm pixel pitch. The long term goal of PixFEL will be the development of a versatile X-ray camera to be operated either in burst mode (European XFEL), or in continuous mode to cope with the high frame rates foreseen for the upgrade phase of the LCLS-II at SLAC.

The PixFEL project is conceived as the first stage of a long term research program aiming at the development of advanced X-ray imaging instrumentation for applications at the free electron laser (FEL) facilities. The project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging by exploring cutting-edge solutions for sensor development, for integration processes and for readout channel architectures. The main focus is on the development of the fundamental microelectronic building blocks for detector readout and on the technologies for the assembly of a multilayer module with minimum dead area. This work serves the purpose of introducing the main features of the project, together with the simulation results leading to the first prototyping run.

We report on the design and TCAD simulations of planar p-on-n sensors with active edge aimed at a four-side buttable X-ray detector module for future FEL applications. Edge terminations with different number of guard rings were designed to find the best trade-off between breakdown voltage and border gap size. The methodology of the sensor design, the optimization of the most relevant parameters to maximize the breakdown voltage and the final layout are described.

In this work we propose the application of a radiation damage model based on the introduction of deep level traps/recombination centers suitable for device level numerical simulation of radiation detectors at very high fluences (e.g. 1{\div}2 10^16 1-MeV equivalent neutrons per square centimeter) combined with a surface damage model developed by using experimental parameters extracted from measurements from gamma irradiated p-type dedicated test structures., Comment: 6 pages,12 figures. arXiv admin note: text overlap with arXiv:1611.10138

We report on the 3-year INFN ATLAS-CMS joint research activity in collaboration with FBK, started in 2014, and aimed at the development of new thin pixel detectors for the High Luminosity LHC Phase-2 upgrades. The program is concerned with both 3D and planar active-edge pixel sensors to be made on 6-inch p-type wafers. The technology and the design will be optimized and qualified for extreme radiation hardness (2e16 neq cm-2). Pixel layouts compatible with present (for testing) and future (RD53 65nm) front-end chips of ATLAS and CMS are considered. The paper covers the main aspects of the research program, from the sensor design and fabrication technology, to the results of initial tests performed on the first prototypes., Comment: 4 pages, 7 figures, 2015 Pisa Meeting

Low-Gain Avalanche Diodes (LGAD) are silicon detectors with output signals that are about a factor of 10 larger than those of traditional sensors. In this paper we analyze how the design of LGAD can be optimized to exploit their increased output signal to reach optimum timing performances. Our simulations show that these sensors, the so-called Ultra-Fast Silicon Detectors (UFSD), will be able to reach a time resolution factor of 10 better than that of traditional silicon sensors.

A CMOS image sensor providing an ultrawide dynamic range with a piecewise linear response is presented. The active pixel is based on a novel architecture which implements a voltage comparator and an analog memory to detect and store the information on the integration time needed to reach saturation, while also maintaining the standard integrated photo-current signal. A 128/spl times/64 pixel array has been designed and fabricated in 0.35-/spl mu/m, 3.3-V CMOS technology. The chip measures 2.67/spl times/4.90 mm/sup 2/ with a pixel size of 24.65/spl times/24.65 /spl mu/m/sup 2/ and a fill factor of about 11%. The sensor has been fully characterized and the measured dynamic range turned out to be 132 dB with a power consumption of 14 mW at video frame rate. The sensor features also good noise performance with a temporal noise of 0.2% (1.7%) and a fixed pattern noise of 0.4% (1.5%) at low (high) irradiance.

International audience; The very high fluences (e.g. up to $2 \times 10^{16} 1$ MeV $n_{eq}/cm^{2}$) and total ionising doses (TID) of the order of 1 Grad, expected at the High Luminosity LHC (HL-LHC), impose new challenges for the design of effective, radiation resistant detectors. Ionising energy loss is the dominant effect for what concerns SiO$_{2}$ and SiO$_{2}$/Si interface radiation damage. In particular, surface damage can create a positive charge layer near the SiO$_{2}$/Si interface and interface traps along the SiO$_{2}$/Si interface, which strongly influence the breakdown voltage, the inter-electrode isolation and capacitance, and might also impact the charge collection properties of silicon sensors. To better understand in a comprehensive framework the complex and articulated phenomena related to surface damage at these very high doses, measurements on test structures have been carried out in this work (e.g. C–V and I–V). In particular, we have studied the properties of the SiO$_{2}$ layer and of the SiO$_{2}$/Si interface, using MOS capacitors, gated diodes (GD) and MOSFETs manufactured by FBK on high-resistivity n-type and p-type silicon, before and after irradiation with X-rays in the range from 50 krad(SiO$_{2}$) to 20 Mrad(SiO$_{2}$). Relevant parameters have been determined for all the tested devices, converging in the oxide charge density NOX, the surface generation velocity s0 and the integrated interface-trap density NIT dose-dependent values. These parameters have been extracted to both characterize the technology as a function of the dose and to be used in TCAD simulations for the surface damage effect modeling and the analysis and optimization of different classes of detectors for the next HEP experiments.

We describe our experience on design and fabrication, on high-resistivity silicon substrates, of microstrip detectors and integrated electronics, devoted to high-energy physics experiments and medical/industrial imaging applications. We report on the full program of our collaboration, with particular regards to the tuning of a new fabrication process, allowing for the production of good quality transistors, while keeping under control the basic detector parameters, such as leakage current. Experimental results on JFET and bipolar transistors are presented, and a microstrip detector with an integrated JFET in source–follower configuration is introduced.

In this paper we propose a portable instrument for alpha-particle detection based on a previously-developed BJT detector and a simple, IC-based readout electronics. Experimental tests of the BJT detector and readout electronics are reported. Numerical simulations are adopted to predict the performance enhancement achievable with optimized BJT detectors.

For the unprecedentedly high radiation level at the sLHC, the luminosity upgrade of the LHC, new tracking detectors are investigated. Among different approaches, silicon detectors in 3D technology constitute a promising option. Columnar electrodes are etched into the substrate, therefore the distance for charge collection and depletion is decoupled from the detector thickness. Thus, two of the detrimental effects caused by radiation in silicon (increased depletion voltage and charge carrier trapping) can be reduced. Results of measurements with irradiated 3D silicon strip detectors produced by IMB-CNM are presented.

The PixFEL project is conceived as the first stage of a long term research program aiming at the development of advanced instrumentation for coherent X-ray diffractive imaging applications at the next generation free electron laser (FEL) facilities. The project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging through the adoption of cutting-edge microelectronic technologies and innovative design and architectural solutions. For this purpose, the collaboration is developing the fundamental microelectronic building blocks (low noise analog front-end with dynamic compression feature, high resolution, low power ADC, high density memories) and investigating and implementing the enabling technologies (active edge pixel sensors, high density and low density through silicon vias) for the assembly of a multilayer four side buttable tile. The building block design is being carried out in a 65 nm CMOS technology. The ambitious goal of the research program is the fabrication of an X-ray camera with single photon resolution, 1 to 104 photons @ 1 keV to 10 keV input dynamic range, 1 kevent in-pixel memory, 100 µm pixel pitch, and the capability to be operated at the fast (1 MHz or larger) rates foreseen for the future X-ray FEL machines.

This work presents the design of a read-out channel suitable for application to silicon pixel detectors for the next generation Free Electron Laser (FEL) experiments. The readout architecture, which has been carried out in a 65 nm CMOS technology, consists of a low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time-variant shaping stage and a low-power analog-to-digital converter (ADC), hosted in a 100 µm-pitch pixel. The blocks will be operated in such a way to cope with the high frame rates (exceeding 1 MHz) foreseen for future X-ray FEL machines. The paper describes in detail the architecture and the performance of the CSA and provides an overview about the analog readout channel.

In preparation for the tenfold luminosity upgrade of the Large Hadron Collider (the HL-LHC) around 2020, three-dimensional (3D) silicon pixel sensors are being developed as a radiation-hard candidate to replace the planar ones currently being used in the CMS pixel detector. This study examines an early batch of FBK sensors (named ATLAS08) of three 3D pixel geometries: 1E, 2E, and 4E, which respectively contain one, two, and four readout electrodes for each pixel, passing completely through the bulk. We present electrical characteristics and beam test performance results for each detector before and after irradiation. The maximum fluence applied is 3.5×1015 n eq /cm2.

The fabrication of Avalanche Photodiodes (APDs) in CMOS processes can be exploited in several application domains, including telecommunications, time-resolved optical detection and scintillation detection. CMOS integration allows the realization of systems with a high degree of parallelization which are competitive with hybrid solutions in terms of cost and complexity. In this work, we present a linear-mode APD fabricated in a 0.15μm process, and report its gain and noise characterization. The experimental observations can be accurately predicted using Hayat dead-space noise model. Device simulations based on dead-space model are then used to discuss the current status and the perspectives for the integration of high-performance low-noise devices in standard CMOS processes.

A compact, analytical model is derived for the n-side interstrip resistance of double-sided silicon microstrip detectors, allowing for fast and accurate prediction of the minimum p-stop (or p-spray) implant dose ensuring adequate interstrip isolation. The basic idea on which the proposed model relies is that the portion of the detector between two adjacent n-strips can effectively be reduced to an equivalent n-channel MOSFET. The interstrip resistance can be evaluated as the output resistance of this equivalent MOSFET using standard SPICE-like models. The influence of radiation-induced oxide charge and p-stop (or p-spray) voltage can be accounted for by simply including, in the threshold voltage expression, the induced flat-band voltage shift and body-effect term, respectively.

We report on the development of a fabrication technology for n-on-n silicon pixel detectors oriented to the ATLAS experiment at LHC. The main processing issues and some selected results from the electrical characterization of detector prototypes and related test structures are presented and discussed.

We report on the development of double-sided, AC-coupled, microstrip detectors oriented to the A Large Ion Collider Experiment (ALICE). The main design and processing issues are presented, together with some selected results from the electrical characterization of detectors and related test structures.

We report on the design and characterization of a full-analog programmable current-mode cellular neural network (CNN) in CMOS technology. In the proposed CNN, a novel cell-core topology, which allows for an easy programming of both feedback and control templates over a wide range of values, including all those required for many signal processing tasks, is employed. The CMOS implementation of this network features both low-power consumption and small-area occupation, making it suitable for the realization of large cell-grid sizes. Device level and Monte Carlo simulations of the network proved that the proposed CNN can be successfully adopted for several applications in both grey-scale and binary image processing tasks. Results from the characterization of a preliminary CNN test-chip (8×1 array), intended as a simple demonstrator of the proposed circuit technique, are also reported and discussed. Copyright © 2001 John Wiley & Sons, Ltd.

Modern experiments search for extremely rare processes hidden in much larger background levels. As the experiment complexity, the accelerator backgrounds and luminosity increase we need increasingly exclusive selections to efficiently select the rare events inside the huge background. We present a fast, high-quality, trackbased event selection for the self-triggered SLIM5 silicon telescope. This is an R&D experiment whose innovative trigger will show that high rejection factors and manageable trigger rates can be achieved using finegranularity, low-material tracking detectors. This strategy requires massive computing power to minimize the online execution time of complex tracking algorithms. Affordable latency and rates are provided by a dedicated device, the Associative Memory (AM). The time consuming pattern recognition problem, generally referred to as the “combinatorial challenge”, is beat by the AM exploiting parallelism to the maximum level: it compares the event to precalculated “expectations” (pattern matching) at once. This approach reduces to linear the typical exponential complexity of the CPUbased algorithms. The problem is solved by the time data are loaded into the AM devices. We describe the AM-based trigger and its successful use in the SLIM5 test beam where a silicon detector telescope has been recently tested on the CERN SPS beam.

The silicon photomultiplier (SiPM) is one of the most interesting solid-state detectors for very low-level light detection featuring extremely fast timing response. In FBK we manufactured SiPMs with different micro-cell proprieties such as: size, layout and epi-layer thickness. We characterized both statically and dynamically all devices to understand the impact of each parameter on the signal shape and charge. In this paper we report on the impact of the metal layer layout on the signal shape and gain. We will show both experimental results as well as SPICE simulations.

In the past few years we have developed 3D detector technologies within a collaboration between INFN and FBK-irst aiming at a simplification of the fabrication technology with respect to the original 3D design. These detectors are the object of an increasing interest from the HEP community because of their intrinsic radiation hardness, making them appealing for innermost layers of tracking at the foreseen upgrades of the large hadron collider. In this paper we evaluate the signal shape in response to localized and uniform charge deposition both by solving Ramo's theorem and with the aid of TCAD simulations. Signals observed in 3D diodes, stimulated by lasers at different wavelengths, are compared with simulations results.

We report on the definition and the implementation in ANACAD Eldo simulator of a photodiode circuit macro-model to be used in the design of optical smart sensors such as position sensing detectors (PSDs) and digital cameras. The optical power waveform as well as its spectrum can be easily defined by the user, allowing for a high flexibility of the model. The effectiveness of the proposed macro-model is highlighted by comparing Eldo simulation results with both numerical device simulation results and experimental data.

A theoretical study is presented showing that the reverse leakage current thermally generated at the cutting edge of type-inverted p/sup +/-n single-sided silicon microstrip detectors is limited. Such behaviour is shown to be related to a self-limiting mechanism acting on the edge surface generation, which prevents the net generation rate of electron-hole pairs at the detector edge from exceeding a saturation value, as the local hole density approaches its equilibrium value.

We show that in high-resistivity silicon bulk generation lifetime and surface generation velocity can not be measured with acceptable accuracy using a single gated diode, unless the gate length is suitably tailored. The accuracy with which bulk generation lifetime can be evaluated is, in particular, limited by nonidealities, contributing extra components to the gated-diode current, which are not accounted for in the standard extraction procedure.

In this article, we show that a p-channel silicon Junction Field Effect Transistors (JFET) can be obtained within a conventional CMOS n-well technology with no additional process steps but a simple layout modification of the p-channel-stop mask; in fact, in the suggested technology, the p-channel of the JFET is obtained by using the same CMOS p-stop implantation step. Results from the electrical characterization of a specially designed test-chip confirmed the validity of the device concept and its full compatibility with CMOS devices; in particular, JFETs exhibit high transconductance and output resistance as well as low gate current and input capacitance. The proposed technological approach has therefore proved to be suitable for the realization of p-JFET–CMOS low-noise circuits.

In the past two years, we have developed 3D detector technologies at ITC-irst (Trento, Italy). We have proposed a new 3D architecture, having columnar electrodes of one doping type only, allowing for a simplified fabrication process. In this paper, we report on preliminary results from the electrical characterization of devices irradiated with neutrons, showing that low depletion voltage values can be achieved even after very large fluences.

The electrical reliability of integrated capacitors to be used for AC-coupled microstrip detectors has been investigated by characterizing a specially designed test chip. Capacitors employing different stacked dielectrics, including double-layer oxide, oxide-nitride, and oxide-nitride-oxide insulators, have been compared in terms of intrinsic breakdown field and extrinsic failure distributions. Results obtained from two fabrication runs are presented and discussed. The impact of the different technological options adopted on diode leakage current and bulk- and surface-generation parameters is also reported.

PIN diodes and other test structures have been fabricated on both n- and p-type, high-resistivity, Floating-Zone (FZ) silicon substrates. Different alternative extrinsic-gettering techniques have been adopted to the purpose of meeting the required specification of a detector leakage current density lower than 1 nA/cm2. Phosphorus-doped polysilicon gettering provided the best results on n-type Si with a leakage current density lower than 0.2 nA/cm2 at 100 μm depletion width. On the contrary, devices made on p-type substrates exhibited a leakage current density two orders of magnitude higher. A proper control of the oxide charge at the silicon-silicon dioxide interface was found to be crucial in obtaining a predictable behavior of PIN diode detectors. Some degradation of the reverse leakage current has been observed after device dicing and bonding.

In the past few years we have developed a technological process allowing for the fabrication of radiation detectors with integrated electronics on high-resistivity silicon substrates. We report on some recent results relevant to the process optimisation and to device/circuit characterization.

We report on selected results from the production of 400 double-sided silicon microstrip detectors for the AMS-02 experiment. The main process issues are discussed with emphasis on their impact on detector performance and fabrication yield.

Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper., Comment: RESMDD12 Proceedings, preprint submitted to Nuclear Instruments and Methods A

A battery-powered, wireless Radon sensor has been designed and realized using a BJT, fabricated on a high-resistivity-silicon substrate, as a radiation detector. Radon daughters are electrostatically collected on the detector surface. Thanks to the BJT internal amplification, real-time α particle detection is possible using simple readout electronics, which records the particle arrival time and charge. Functional tests at known Radon concentrations, demonstrated a sensitivity up to 4.9 cph/(100 Bq/m3) and a count rate of 0.05 cph at nominally-zero Radon concentration. © 2012 Elsevier B.V. All rights reserved.