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A new version of the CLARO8 ASIC has been designed in AMS 0.35 μm CMOS technology, based on radiation hardened by design cells, and extensively tested. Results on the complete radiation hardness characterization are presented. more...

Radiation hardness tests of the CLARO8 ASIC, designed in AMS 0.35micron CMOS technology for the upgrade of the CERN LHCb RICH detectors, are presented, including measurements of total- ionizing dose and single event effects. more...

We report on the electrical behavior of termination structures for silicon diodes irradiated with high-energy particles. In particular, the analysis is focused on samples featuring an all-P-type (APT) termination structure that has already been proved to yield excellent long-term stability performance. The radiation hardness of these structures is compared to that of more common reference devices. In order to characterize various radiation conditions, tests were performed using protons, neutrons, and high-energy electrons with different fluences up to values causing substrate type inversion. We verified that the APT samples remain functional in all the considered situations, their operational limit being comparable to that of the other devices. more...

Single photon avalanche diodes (SPADs) have been recently studied as photodetectors for applications in space missions. In this presentation we report the results of radiation hardness test on large area SPAD (actual results refer to SPADs having 500 mu m diameter). Dark counts rate as low as few kHz at -10 degrees C has been obtained for the 500 mu m devices, before irradiation. We performed bulk damage and total dose radiation tests with protons and gamma-rays in order to evaluate their radiation hardness properties and their suitability for application in a Low Earth Orbit (LEO) space mission. With this aim SPAD devices have been irradiated using up to 20 krad total dose with gamma-rays and 5 krad with protons. The test performed show that large area SPADs are very sensitive to proton doses as low as 2 x 10(8) (1 MeV eq) n/cm(2) with a significant increase in dark counts rate (DCR) as well as in the manifestation of the "random telegraph signal" effect. Annealing studies at room temperature (RT) and at 80 degrees C have been carried out, showing a high decrease of DCR after 24-48 h at RT. Lower protons doses in the range 1-10 x 10(7) (1 MeV eq) n/cm(2) result in a lower increase of DCR suggesting that the large-area SPADs tested in this study are well suitable for application in low-inclination LEO, particularly useful for gamma-ray astrophysics. (c) 2013 Elsevier B.V. All rights reserved. more...

Recent results from the CERN RD50 Collaboration for the development of radiation-hard detectors for the LHC upgrade (Super-LHC) and in general for very high luminosity colliders are reported and discussed. Particularly, the attention is focused on Czochralski and Magnetic Czochralski silicon, thin detectors and p-type substrate devices. more...

We irradiated programmed Floating Gate (FG) memory arrays with different radiation sources, including 10 keV X-rays, /sup 60/Co /spl gamma/-rays, and 27 MeV protons. After irradiation, FGs experience a net charge loss which can degrade the stored information in terms of MOSFET threshold voltage. The charge loss is the result of two different phenomena: charge generation/recombination in the oxides and photoemission from the FG. The threshold voltage shift in irradiated devices depends on the radiation source: strong dose enhancement phenomena were found after X-ray irradiation, whereas proton results closely follow /spl gamma/-ray results. more...

For the construction of the silicon microstrip detectors for the Tracker of the CMS experiment, two different substrate choices were investigated: A high-resistivity (6 k cm) substrate with (111) crystalorientation and a low-resistivity (2k cm) one with (100) crystalorientation. The interstrip and backplane capacitances were measured before and after the exposure to radiation in a range of strip pitches from 60 μm to 240 μm and for values of the width-over-pitch ratio between 0.1 and 0.5. more...

The charge trapping properties of 8 nm thick oxide layers of metal-oxide-semiconductor capacitors have been studied before and after 8 MeV electron irradiation as a function of the radiation dose. The positive charge induced by ionizing radiation increases with the radiation dose without saturation up to 20 Mrad(Si). It does not disappear at room temperature even 10 days after the irradiation, but it annihilates by recombination if electrons are injected into the oxide by Fowler–Nordheim tunneling. After the positive charge recombination, we have observed, by capacitance–voltage and current–voltage measurements, increased electron trapping in the irradiated oxides, due to the neutral traps generated by radiation. The negative trapped charge increases linearly with the radiation dose, and its centroid is close to the center of the oxide but shifted to the gate/SiO 2 interface. Finally, the oxide degradation of irradiated and unirradiated devices by constant current stress has been measured: differences between irradiated and unirradiated devices disappear for fluences larger than 10 19 electrons/cm 2 . more...

The SIRAD irradiation facility is located at the Tandem-ALPI accelerating system of the INFN National Laboratories of Legnaro, Italy. SIRAD is devoted to Single Event Effects and bulk damage studies on semiconductor detectors and electronic devices and systems. Here we describe the status of SIRAD by reporting the characteristics of the ion beams, of the irradiation chamber and of the monitoring and dosimetry systems for particle fluence measurements. The Ion Electron Emission Microscope which allows micrometric SEE sensitivity mapping is also briefly described. Single Event Upset (SEU) cross-section measurements of the ESA SEU monitor, presented here, show full compatibility with those obtained at irradiation facilities supported by ESA. more...

In silicon material with oxygen concentration in the range (4–9)×10 17 cm −3 , grown by the CZ method and irradiated by reactor neutrons, the interstitial oxygen mainly participates in A-center (V+O) creation. A-center concentration is linearly dependent on neutron fluence up to Φ =10 18 n/cm 2 , value at which saturation occurs caused not by the exhaustion of dissolved oxygen but rather by vacancy-interstitial atom annihilation competitive mechanisms. A-center annealing ( T >300°C) does not lead to the full restoring of interstitial oxygen concentration. Repeating neutron irradiation and annealing causes a decrease of oxygen complex activity and the silicon behaves as a low-oxygen material. more...

We study the possibility to use Single Photon Avalanche Diodes (SPADs) optically coupled to scintillating fibers as a novel type of gamma-ray detector for space applications. SPADs are silicon devices operating under polarization conditions above the junction breakdown voltage (typical overvoltage of 5V), for which a single photon interacting in the active region is sufficient to trigger a self sustainable avalanche discharge. SPADs can thus be used for the detection of very low light levels with an absolute timing accuracy of about 30 ps for single photon detection, without spectroscopic capabilities. In this presentation we report the preliminary results on large area SPAD (actual results refers to SPADs having 200 ?m diameter, with the aim to grow up to 500 ?m SPADs) coupled to scintillating fibers as the basic module for a particle tracker for space application. Dark counts rate as low as few tens of kHz at room temperature, lowering down to few kHz at -10°C have been obtained for the 200 ?m devices, in accordance with the basic requirements for the proposed application. Similar instruments based on silicon photomultiplier (SiPM) readout have already been studied, but none based on SPAD has been realized up to now. Moreover, since very few information is available on SPADs for the use in a space environment, we performed bulk damage and total dose radiation tests with protons and gamma-rays in order to evaluate their radiation hardness properties and their suitability for application in a Low Earth Orbit (LEO) space mission. With this aim the SPAD devices have be irradiated using up to 20 krad total dose with gamma-rays and 5 krad with protons more...

The XAA1.2 is a custom ASIC chip for space applications built using a 0.8 μ m complementary metal oxide semiconductor technology on epitaxial layer. It has been selected as the front-end electronics chip of the SuperAGILE experiment on board the AGILE space mission, although it is not specifically designed as a radiation hard device. To study the XAA1.2 sensitivity to Single Event Effects and Total Dose Effects we irradiate this chip at the SIRAD facility of the Laboratori Nazionali INFN of Legnaro. In this paper we describe the experimental set-up and the measurements. We then discuss how the results can be scaled to the cosmic rays environment in a low-Earth orbit. more...

A heavy ion radiation test has been performed to evaluate the SEU sensitivity of Virtex devices. Differently from previous radiation tests, the one here described specifically addresses configuration logic. Previously unreported failure mechanisms have been observed and classified and their corresponding cross sections measured. more...

In the high energy physics experiments at the CERN Large Hadron Collider, the silicon detectors will suffer high radiation damage due to the large hadron (pions, protons and neutrons) fluences. It has been estimated that fluences up to 1.6 10 1-MeV equivalent neutrons/cm are expected in the 10 years of operation for the silicon strip tracker of the CMS experiment (CMS collaboration, 1998). Radiation damage causes degradation of the detector performance due to: (a) the monotonic increase of the reverse leakage current, (b) the increase of the detector depletion voltage (Vdep), after substrate space charge sign inversion due to deep acceptor generations. The ROSE Collaboration (Lindstrom et al., 2001) at CERN has widely investigated how the Vdep increase can be mitigated by introduction of impurities in the silicon substrate. Particularly, high oxygen concentrations ([O]>10 cm ) drastically reduce the Vdep increase for charged hadron (protons and pions) irradiation, whereas no such effect is observed after neutron irradiation (Lindstrom et al., 2001). In this study we present the characteristics of the bulk damage degradation induced by protons and neutrons with different energy spectra, in silicon detectors produced by various manufacturers on standard and oxygenated silicon substrates. This summary highlight the state of the art for technologies in detector radiation hardening for high energy physics applications. more...

SuperAGILE is the X-ray instrument of the AGILE Mission. It is a set of silicon micro-strip detectors tiles coupled with atungsten coded mask. The front end electronics of SuperAGILE is based on 48 ASIC XAA1.2 chips, each one collectingand conditioning the signals from 128 strips of the detector. Since this chip was not developed as a radiation resistantcomponent for space applications and in order to predict and prevent the potential problems deriving from the spaceradiation environment, we irradiated two of such chips with ions of different chemical specie, ranging from 16 O to 127 I. Atthe 15 MV Tandem accelerator of the Laboratori Nazionali INFN di Legnaro we measured the occurrence of latch-up andSingle Event Upset and the effects due to the absorbed total dose on the supply currents and on the bias currents whichcontrol the performances of the chip. In this paper we discuss how the results can be scaled to the AGILE environment andthe impact of these data on the experiment design and on the observing strategy.Keywords : High Energy Astrophysics, X-rays, Radiation damage, ASIC more...

We report on the electrical behavior of termination structures for silicon diodes irradiated with high-energy particles. In particular, the analysis is focused on samples featuring an All-P-Type (APT) termination structure, that has already been proved to yield excellent long-term stability performance. The radiation hardness of these structures is compared to that of standard devices. In order to characterise various radiation conditions, tests were performed using protons, neutrons, and high-energy electrons with different fluences up to values causing substrate type inversion. We verified that the APT samples remain functional in all the considered situations, their operational limit being comparable to that of standard devices. more...

We investigated the charge trapping properties of 10 nm thick oxide metal-oxide-semiconductor capacitors after 158 MeV silicon ion beam exposure up to 20 Mrad(Si) dose. Devices were biased during irradiation by a positive or negative gate voltage to drift radiation induced holes to the silicon/oxide and gate/oxide interface, respectively. Experimental results show that the radiation induced effective positive charge increases linearly with dose and is larger for the positive biased devices. The positive charge recombines with electrons injected in the oxide by Fowler–Nordheim tunnelling. After positive charge recombination a net negative charge builds up, due to electron trapping in radiation induced neutral defects. The negative charge density increases linearly with dose and it is larger for positive biased devices. The negative charge centroid is close to the oxide centre. The probability that one effective negative charge is generated by one radiation induced effective positive charge is 0.153±0.005. more...

We have investigated the degradation of MOS structure due to high energy electron irradiation as a function of radiation dose and gate bias applied during the irradiation. Devices have been characterized by current–voltage measurements, in order to study charge accumulation also at the gate interface. Three types of oxide charge have been observed: the unstable positive charge, due to trapped holes induced by the electron irradiation; the negative charge in the oxide bulk, deriving from capture of electrons injected during electrical measurements in radiation generated traps; and border traps, at both oxide interfaces. more...

Multiguard structures are used in order to enhance the breakdown voltage of microstrip detectors. In this work we studied the electrical properties of devices designed in four different layouts on n-Si substrates, based on a central diode surrounded by various p/sup +/ and/or n/sup +/ floating rings. In particular we measured the main DC characteristics and we compared the experimental results with those simulated by a two-dimensional drift-diffusion computer model. Device noise was also measured for the central diode as a function of the applied voltage. We repeated all measurements after neutron and gamma irradiation, in view of the application of these devices to silicon microstrip detectors for future high energy physics experiments. For example at the LHC the level of radiation damage expected during the detector lifetime implies very high bias voltages for the detector operation. Multiguards can offer a solution, provided the optimisation of the design takes into account the radiation effects. more...

Future high energy physics experiments will make large use of silicon detectors both for tracking and vertexing purposes. Due to the very high radiation environment in which they have to operate, many studies have been carried out with the aim of extrapolating from radiation damaged diodes data the lifetime of silicon detectors. Here we present data collected with 190 MeV pions and 300 MeV protons for diodes of different resistivities and manufactures. Changes in full depletion voltage and leakage current have been studied at 5°C and room temperature up to fluences of 10 14 cm −2 . Our data show that lower resistivity diodes have the same leakage current damage constant but a longer lifetime in terms of change in depletion voltage. We also confirm that 190 MeV pions are more damaging than 3000 MeV protons in terms of both effective doping concentration and leakage current. more...

We have studied the effects of ionizing and non-ionizing radiation on the breakdown properties of different types of MOS capacitors, with thick (200 nm) and thin (down to 8 nm) oxides. In general, no large variations of the average breakdown field, time-to-breakdown at constant voltage, or charge-to-breakdown values have been observed after high dose irradiation (20 Mrad(Si) 9 MeV electrons on thin and thick oxides, 17(Si) Mrad Co/sup 60/ gamma and 10/sup 14/ neutrons/cm/sup 2/ only on thick oxides). However, some modifications of the cumulative failure distributions have been observed in a few of the oxides tested. more...

We have largely improved the performance of our detector-compatible Si JFETs by optimizing the fabrication technology. New devices feature thermal noise values close to the theoretical ones, and remarkably low 1/f noise figures. In view of adopting these JFETs for X-ray imaging and HEP applications, bulk and surface radiation damage tests have been carried out by irradiating single transistors and test structures with neutrons and X-rays. Selected results from static and noise characterization of irradiated devices are discussed in this paper, and the impact of radiation effects on the performance of JFET-based circuits is addressed. more...

The ways of increasing the radiation hardness of silicon were considered. It was then experimentally shown that a preliminary irradiation of the bulk silicon introduces sinks for radiation defects that leads to an increased radiation hardness of the silicon. Neutron transmutation doping of silicon can be considered as one form of preliminary radiation. It was shown that for neutron transmutated silicon the carrier removal rate in NTD after /spl gamma/-irradiation is more than one order of magnitude smaller than in a standard reference specimen, but the carriers removal rate after neutron irradiation is approximately a factor of two less. more...

High Energy Physics experiments at future very high luminosity colliders will require ultra radiation-hard silicon detectors that can withstand fast hadron fluences up to 10/sup 16/ cm/sup -2/. In order to test the detectors radiation hardness in this fluence range, long irradiation times are required at the currently available proton irradiation facilities. Energetic (58 MeV) Lithium (Li) ions, with experimental hardness factor about two orders of magnitude higher than 24 GeV protons for 280-300 /spl mu/m thick detectors, could represent a promising alternative radiation source. In this study, the degradation mechanisms in single pad p/sup +/-n Standard Float Zone (STFZ) and Diffusion Oxygenated Float Zone (DOFZ) Si detectors irradiated with Li ions up to the fluence of 2.9/spl times/10/sup 12/ Li/cm/sup 2/ have been investigated by means of Photo Induced Current Transient Spectroscopy and Thermally Stimulated Currents. Results are compared with the radiation damage induced by 24 GeV proton, 1 MeV neutron and /sup 60/Co /spl gamma/-ray irradiation. The critical Li ion fluence for cluster formation is found to be in the range 4.1-21/spl times/10/sup 11/ Li/cm/sup 2/ and its correlation to the corresponding value for hadrons is discussed. more...