The ASTOR instrument is a state-of-the-art neutron imaging instrument being developed by LAHN (Laboratorio Argentino de Haces de Neutrones or Argentinian Laboratory of Neutron Beams) to be installed on one of the cold neutron beams of the 30MW open pool reactor RA-10, currently under construction at the outskirts of Buenos Aires. ASTOR will have direct view to a D 2 cold source and will include a primary collimator at 2.5m from its surface. Its design includes a beam conformation room with a set of exchangeable secondary collimators to further collimate the beam, and several devices (solid state filters, a velocity selector and a double crystal monochromator) to tailor the energy spectrum for specific applications. Downstream the beam, it will have an experimental room with ample space for objects and samples, and L/D ratios in the range 120-1500 with calculated fluxes of 3.7 x 10 8 n/cm 2 s and 2.4 x 10 6 n/cm 2 s respectively (E<25meV) and a maximum field of view of 25x25 cm 2 . It will also count with two rectangular pinholes to obtain increased resolution in one dimension without substantially decreasing the flux.

The characteristic energies of traps in InAlN/AlN/GaN high-electron mobility transistor structures on Si(111) substrates formed after irradiation with 75 MeV S-ions are studied by means of c-lattice parameter analysis, vertical IV-characteristics, micro-photoluminescence (µ-PL), photocurrent (PC) and thermally stimulated current (TSC) spectroscopy. From the lattice parameter analysis, point defect formation is concluded to be the dominant source of defects upon irradiation. A strong compensation effect manifests itself through enhanced resistivity of the devices as found in vertical IV-measurements. Defect formation is detected optically by an additional PL-band within the green spectral region, while defect states with threshold energies at 2.9 eV and 2.65 eV were observed by PC spectroscopy. The TSC spectra exhibit two defect-related emissions between 300 K and 400 K with thermal activation energies of 0.78–0.82 eV and 0.91–0.98 eV, respectively. The data further supports the formation of Ga vacancies (V Ga) and related complexes acting mainly as acceptors compensating the originally undoped n-type GaN buffer layers after irradiation.

The breakdown (BD) sequence in high-K/interfacial layer (HK/IL) stacks for time-dependent dielectric breakdown (TDDB) has remained controversial for sub-45 nm CMOS nodes, as many attempts to decode it were not based on proper experimental methods. Know-how of this sequence is critical to the future design for reliability of FinFETs and nanosheet transistors. We present here the use of radiation fluence as a tool to precisely tune the defect density in the dielectric layer, which jointly with the statistical study of the soft, progressive and hard BD, allow us to infer the BD sequence using a single HfO 2 –SiO x bilayered MOS structure.

AlInN/GaN on Si high-electron mobility transistors (HEMTs) are irradiated with various fluences of 75-MeV sulfur ions to study the radiation-induced degradation mechanisms. Heavy-ion irradiation has been found to reduce saturation ON- and OFF-state current and, at higher fluence, to induce a large positive threshold voltage shift. Irradiated structures reveal a consistent carrier density and mobility reduction as a function of fluence. To demonstrate the buffer-induced threshold shift, a series of samples with various GaN channel layer thicknesses defined by carbon-doped GaN buffer layers are characterized. By comparison of the threshold voltage of nonirradiated devices with reduced channel layer thickness, we assign the observed effects mainly to carrier depletion. Thus, formation of acceptor-like traps upon irradiation is concluded as primary degradation mechanism in GaN-based HEMTs. AlInN/GaN HEMT structures are, therefore, more tolerant to heavy-ion irradiation than AlGaN/GaN transistors as their intrinsic channel conductivity is higher.

In this paper, charge-sharing effects on analog single-event transients are experimentally observed in a fully custom designed, 180-nm complementary metal-oxide-semiconductor (CMOS) operational amplifier by means of a heavy-ion microbeam. Sensitive nodes of the differential stage showed bipolar output transients that cannot be explained by single-node collection for the closed-loop characteristics of the circuit under test. The layout of these transistors is consistent with charge-sharing effects due to deposited charge diffusion. Implementation of linear modeling and simulations of multiple node collection between paired transistors of the input stage showed great coincidence with the obtained experimental wave-forms, shaped as bipolar, quenched pulses. These effects are also observed due to dummy transistors placed in the layout. A simple parametrization at the simulation level is proposed to reproduce the observed experimental waveforms. Results indicate that charge-sharing effects should be taken into account during simulation-based sensitivity evaluation of analog circuits, as pulse quenching can alter the obtained results, and linear modeling is a simple approach to emulate simultaneous charge collection in multiple nodes by applying superposition principles, with aims of hardening a design.

AlInN/GaN heterostructure field-effect transistors (HFETs) grown on silicon withstand irradiation with 75-MeV sulfur ions up to fluences of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.5 \times 10 ^{13}$ </tex-math></inline-formula> ions/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The static transistor operation characteristics of the devices exhibit a shift of the threshold voltage and a decrease in the saturation and the OFF-state current. Microphotoluminescence spectroscopy reveals a decrease in the electron carrier density in the channel region. Simulations were performed to model the damage caused to the devices assuming the generation of acceptor-like defects upon irradiation. It turns out that the degradation depends on the thickness of the buffer layer. Therefore, we propose the reduction in the thickness of the buffer layer as a way to increase the radiation tolerance of HFETs.

Introducción y objetivos: El mercurio (II) acuoso, Hg2+, es todavía un contaminante peligroso ampliamente distribuido. Las estrategias de fitorremediación son ambientalmente amigables y de bajo costo. Con el fin de optimizar estos procesos, se utilizó Spirodela intermedia, una macrófita acuática autóctona, para remover Hg2+ en agua mineral, en condiciones de laboratorio, estudiando la distribución in vivo de mercurio y otros elementos por mapeo barriendo con una microsonda nuclear.M&M: Las exposiciones (concentraciones de Hg2+ de 1 y 10 mg.L-1) duraron al menos 2 semanas. Los parámetros: tasa de captación, factores de bioconcentración (BCFs) de mercurio en raíces y frondes y factores de translocación (TFs) fueron calculados a partir de cuantificaciones de microPIXE con el acelerador Tandar de Buenos Aires.Resultados: S. intermedia puede ser considerado un hiperacumulador. Los más altos BCFs (> 1000 raíces y > 200 frondes) correspondieron a 1 mg.L-1 a las 96 hs. En todos los casos, se constató que TFs < 1, indicando que no ocurre translocación de Hg2+. Se obtuvieron mapas 2D de alta resolución espacial de la distribución elemental in vivo para las diferentes condiciones. Se observó que la distribución de mercurio en frondes es más heterogénea que en raíces. Fue importante la detección de Hg en clorénquima donde sus efectos son más tóxicos. Se analizó una correlación entre la distribución de mercurio y calcio y la relación con respuestas fisiológicas.Conclusiones: La fitorremediación de Hg2+ con S. intermedia es una alternativa conveniente. Por haberse realizado en agua real, el protocolo es escalable.

Recently we used the heavy ion microprobe of the Buenos Aires TANDAR Laboratory for Single Event Effects (SEE) and Total Dose (TD) experiments in electronics devices and components, requiring very low beam currents. The facility includes a fast beam switch that allows the control of the ion beam current and a mobile Si PIN (p-type, intrinsic, n-type) diode that directly measures the number of ions hitting the device. The fast beam deflector was used to reduce the current by producing a pulsed beam or generating a quasi-continuous (Poisson-like distributed) beam with currents ranging from tens to hundreds of ions/s. As an application for this current control method we present a single event effect (SEE) pulses map generated by a 32S8+ beam at 75 MeV on two 0.5 µm technology CMOS digital output buffers where the device was formed by cascading four CMOS inverters with increasing sizes from input to output to drive large loads. Using the same concept of pulse width modulated deflection, we developed a novel gradient scanning method. This system allows to produce in a single irradiation a distribution with a cumulative damage with a difference of two orders of magnitude at constant gradient. To demonstrate the method, we irradiated a lithium niobate monocrystal with 32S8+ beam at 75 MeV energy and later analyzed the produced damage by the micro-Raman technique and an optical profilometer.

In this work, Spirodela intermedia and Pistia stratiotes, autochthonous floating macrophytes, were used to remove aqueous UO22+ (1 and 10 mg.L-1) under laboratory conditions. The influence of Th4+ (1 mg.L-1) was studied for the highest concentration of U(VI). All the parameters of the bioremediation process, bioconcentration factors (BCFs) in roots and leaves and translocation factors (TFs), were achieved by microPlXE quantification. This analysis was carried out using a 50-MeV O-16(5+) beam with the aid of the heavy-ion microprobe at the TANDAR Laboratory in Buenos Aires. High resolution 2D maps of the in vivo elemental distribution in macrophytes for different conditions were obtained. Both plants have the ability to accumulate a large amount of U(VI) yielding BCFs > 500. Only S. intermedia can additionally uptake Th(IV) reaching a high BCF ( > 300 at 96 h) but the plant does not survive; Th was detected within the chlorenchyma ([Th] congruent to 30 mu g.g(-1)).

In this paper, we analyze the dependence of the Weibull slope (ß) extracted from TDDB tests on HfO2 MOS capacitors (MOSCAPs) on the initial density of defects artificially induced by carefully tuned micro beam irradiation experiments with different carbon dosages. The consistent experimental trend of reducing $p$ with increasing defect density was reproducible only with physics-based breakdown simulations that considered correlated defect generation in HfO2 and localized damage (partial percolation paths) traces created by the impinging ions. Scenarios of spatially random initial defect distribution and random stress-induced defect generation (in space and time) could not explain the experimental trends, confirming that correlated defect generation does exist in HfO2 thereby altering the conventional understanding of TDDB by quite a bit.

An experimental evaluation of the sensitivity to Analog Single Events of a full-custom CMOS Operational Amplifier is reported. The output voltage waveform due to single ion impacts was studied, by scanning the entire area of the circuit under test, using the heavy ion microbeam facility at TANDAR laboratory. A two-dimensional map of the transients captured in the design was obtained, in which the grouping of events in the most sensitive transistors of the circuit can be seen, showing great agreement with results obtained by means of a SPICE simulation environment. Experimental validation of sensitivity provides a better insight into the true resilience against single events of a 180nm technology custom circuit, and shows that the microbeam facility is fit to perform integrated circuit irradiation to extract information down to the single transistor resolution.

Radiation induced currents on single 32 nm MOSFET transistors have been studied using consecutive runs of O-16 at 25 MeV. The main feature is the generation of current peaks - in the gate and channel currents - due to the collection of the electro-hole pairs generated by the incident radiation runs. It has been observed that the incident ions cause damage in the dielectric layer and in the substrate affecting the collection of carriers, and hence the radiation-induced current peaks. It has been find out a decrease of the current peak due to the increase of the series resistance by non-ionizing energy loss in the semiconductor substrate, and an increase of the leakage current due to defects in the gate oxide by ionizing energy loss. For low levels of damage in the gate oxide, the main feature is the shift of the VTH. Hot carriers heated by the incident radiation in the depletion region and injected in the gate oxide cause the change of the V-TH due to electron or hole trapping for n- or p-channel respectively. The overall results illustrate that these effects must be taken into consideration for an accurate reliability projection. (C) 2016 Elsevier Ltd. All rights reserved.

Summary form only given. The radiation exposure of electronic circuits and devices alters their electrical characteristics. When a high-energy particle hits a silicon substrate, and due to coulombian interaction, hole-electron pairs are created. A fraction of these carriers recombine but most of them are swept by the electric field in the depletion regions, generating current pulses that disrupt the normal operation of the circuit. As a consequence, this may lead to a very serious system failures, or progressive performance degradation. When critical missions use these systems, reliability is the main concern, therefore circuits with special considerations must be constructed using techniques for improving radiation tolerance as Radiation Hardening by Design (RHBD) that is cheap and fits well for designs implemented in sub-micron CMOS processes. To check circuit vulnerability of a hardened device different radiation tests must be conducted. For particle interaction tests, one of the most challenging tasks is to perform radiation ground tests that mimics real operation situations. Recently, many efforts have been achieved using laser equipments as in the works of Schwank1 and Palomo2 for transient fault injection, even though, the results must be correlated to heavy ion interaction to validate the approach. In this work, irradiation experiments with heavy-ions in VLSI circuits are reported. We explain how to lower the number of particles per second that reach the circuit, as also to focus the ion beam and control its position to hit on the desired place. We describe the dosimetry as also the measurement methodology. This work demonstrates that the use of a micro-beam line attached to a High-Energy accelerator is suitable for this kind of tests evidencing the validity and robustness of the method.

Testing of single event effects caused by heavy ions in a PLL implemented on a CMOS 90 nm technology is reported in this work. The diagnosis of the circuit vulnerability has been conducted with a heavy ion micro beam line facility at the TANDAR tandem accelerator facility. The accuracy of the positioning system has been evaluated and the radiation dose has been accurately characterized. Single event effects were induced in the circuit and a map of the spatial correlation for the most sensitive blocks has been obtained.

El Micro-haz de iones Pesados (MiP) del laboratorio Tandar constituye un instrumento de características únicas enel país, pues puede proveer haces de iones pesados de dimensiones micrométricas acelerados hasta decenas de MeVde energía. La búsqueda de tamaños de haz más pequeños ha creado la necesidad de contar con estándares decalibración de elevada calidad de resolución. En el presente trabajo se desarrollaron los primeros prototipos paracalibrar la focalización del haz: estructuras metálicas de cobre o niquel en forma de grilla con orificios cuadrados.Se emplearon dos métodos de fabricación. En el primero se utilizaron técnicas de fotolitografía convencional sobreun sustrato de silicio con foto-resina, mientras que en el segundo se utilizó el MiP para micro-mecanizar sustratosde Niobato de Litio (LiNbO3). En ambos casos se finalizó el proceso de fabricación del patrón con electrodeposiciónde cobre o níquel sobre la matriz desarrollada. Mediante la técnica fotolitográfica se fabricaron grillasde níquel que varían entre 130 y 180 mesh**. Mediante micro-mecanizado con el MiP se fabricaron grillas de cobrede entre 500 y 2000 mesh sobre sustratos de LiNbO3.

In order to increase the scanning length of our microprobe, we have developed an irradiation procedure suitable for use in any nuclear microprobe, extending at least up to 400% the length of our heavy ion direct writing facility using standard magnetic exploration. Although this method is limited to patterns of a few millimeters in only one direction, it is useful for the manufacture of curved waveguides, optical devices such Mach–Zehnder modulators, directional couplers as well as channels for micro-fluidic applications. As an example, this technique was applied to the fabrication of 3mm 3D-Mach–Zehnder modulators in lithium niobate with short Y input/output branches and long shaped parallel-capacitor control electrodes. To extend and improve the quality of the machined structures we developed new scanning control software in LabView™ platform. The new code supports an external dose normalization, electrostatic beam blanking and is capable of scanning figures at 16 bit resolution using a National Instruments™ PCI-6731 High-Speed I/O card. A deep and vertical micromachining process using swift 35Cl ions 70MeV bombarding energy and direct write patterning was performed on LiNbO3, a material which exhibits a strong natural anisotropy to conventional etching. The micromachined structures show the feasibility of this method for manufacturing micro-fluidic channels as well.