Alcalde Bessia, F., D. Flandre, N. André, J. Irazoqui, M. Pérez, M. Gómez Berisso, and J. Lipovetzky. "Ultra Low Power Ionizing Dose Sensor Based on Complementary Fully Depleted MOS Transistors for Radiotherapy Application." IEEE Transactions on Nuclear Science (2019): 1.
Abstract: We evaluate the use of the thick buried oxide (BOX) of Fully Depleted Silicon-on-Insulator (FD-SOI) transistors for Total Ionizing Dose (TID) measurements in a radiotherapy application. The devices were fabricated with a custom process in UniversitC) Catholique de Louvain (UCL) which allows to make accumulation mode PMOS transistors and inversion mode NMOS transistors. We characterized the temperature behavior of these devices and the response under X-ray radiation produced by an Elekta radiotherapy linear accelerator, and compared the obtained dose sensitivity to other published works. Taking advantage of these devices, an ultra low power MOS ionizing dose sensor, or MOS dosimeter, with inherent temperature compensation is presented. This dosimeter achieved a sensitivity of 154 mV/Gy with a temperature error factor of 13 mGy/°C and a current consumption below 1 nA.
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Alcalde Bessia, F., D. Flandre, N. André, J. Irazoqui, M. Pérez, M. Gómez Berisso, and J. Lipovetzky. "Fully-Depleted SOI MOSFET Sensors in Accumulation Mode for Total Dose Measurement." In 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC), 1–3. 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC)., 2018.
Abstract: Fully Depleted Silicon-on-Insulator (FD-SOI) transistors fabricated with a custom process in Université Catholique de Louvain (UCL) were irradiated with X-rays using an Elekta Synergy radiotherapy linear accelerator. I-V curves of FD-SOI are sensitive to charges produced in the buried oxide (BOX) by ionizing radiation, so it is possible to use these devices as radiation dosimeters. In this work, we evaluated the use of thick BOX back-gate transistors for Total Ionizing Dose (TID) measurement using different bias conditions and we obtained a maximum sensitivity of 191 mV/Gy for devices operating in accumulation mode.
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Alcalde Bessia, F., M. Pérez, M. Sofo Haro, I. Sidelnik, J. J. Blostein, S. Suárez, P. Pérez, M. Gómez Berisso, and J. Lipovetzky. "Displacement Damage in CMOS Image Sensors After Thermal Neutron Irradiation." IEEE Transactions on Nuclear Science 65, no. 11 (2018): 2793–2801.
Abstract: In this paper, CMOS image sensors were exposed to thermal neutrons observing an increase in the dark signal of many pixels. The effect was found to be similar to the damage caused by alpha particles irradiation. Rutherford backscattering spectroscopy (RBS) and SIMNRA simulation were used to confirm that the sensors contain boron in the insulation layers. The damage produced by thermal neutrons is explained as displacement damage caused by alpha particles and lithium-7 ions in the silicon active volume of the sensors after boron-10 thermal neutron capture.
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Ale Crivillero, M. V., N. Haberkorn, G. Nieva, and J. Guimpel. "Electrical transport properties of FeSe/Fe3O4 bilayers." Materials Today: Proceedings 14 (2019): 18–21.
Abstract: In this work, we study the electronic properties of FeSe/Fe3O4 bilayers deposited onto SrTiO3 (100) and MgO (100) substrates by DC magnetron sputtering. The comparative study of Fe3O4 films grown on SrTiO3 and MgO reveals significant differences in the intensity of the Verwey transition (Tv∼130K). This allows us to probe the impact of the distortions associated to the Verwey transition on the transport properties of the FeSe over-layer in the FeSe/Fe3O4 bilayers. A correlated increase in the resistance and weakened superconducting properties are observed..
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Amigó, M. L., M. V. Ale Crivillero, D. G. Franco, J. Guimpel, and G. Nieva. "Influence of the Fe Concentration on the Superconducting Properties of Fe_{1-y}Se." Journal of Low Temperature Physics 179, no. 1-2 (2015): 15–20.
Abstract: We present a comparative study of electrical transport properties in the normal state and in the dissipative superconducting state between pure TeX -FeSe phase and Fe deficient Fe TeX Se crystals. We discuss the influence of the intergrowth of the magnetic hexagonal phase (Fe TeX Se TeX ) in Fe deficient samples when compared to pure TeX -FeSe samples. In the superconducting state, we measured the TeX -plane electrical resistivity with magnetic field up to 16 T and the electrical resistivity as a function of the angle between the TeX axis and the applied field. The angular dependence at fixed temperature below the superconducting critical temperature, TeX , is very different for both sets of crystals. The Fe deficient samples display a vortex pinning-related feature at TeX 57 TeX off the plane while the pure TeX -FeSe phase samples show the persistence of a strong angular-dependent magnetoresistance characteristic of the normal state electronic structure.
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Belussi, C. H., M. G. Berisso, and Y. Fasano. "Note: Single-polarity high-voltage amplifier to drive coarse-approach slip-stick piezoelectric motors." Review of Scientific Instruments 84, no. 5 (2013): 056104–3.
Abstract: Scanning probe microscopies typically rely on coarse-approach slip-stick piezoelectric motors that work by exciting piezoelectric stacks with sawtooth signals of hundreds of V and some kHz. For this application, we introduce a single-polarity high-voltage amplifier based on discrete MOSFET-technology components with improved output current desirable for low-temperature actuation. The amplifier has an output signal of 600 V, 100 mA output current, noise level below 2 μV/math, 4 kHz high-voltage bandwidth, 2 V/μs slew-rate, and rise and fall times of 80 μs (when loaded with 30 nF). The circuit was successfully applied to drive a home-made scanning tunnelling microscope.
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Berger, S., R. Hauser, H. Michor, G. Hilscher, E. Bauer, J. G. Sereni, and P. Rogl. "Thermodynamic properties of Ce(RuxRh1-x)3B2." Physica B 259-261 (1999): 116–117.
Abstract: Investigations of the magnetic phase diagram of Ce(RuxRh1-x)(3)B-2 were complemented by detailed specific heat and susceptibility measurements revealing complex magnetic order without spontaneous magnetisation. This regime follows the ferromagnetic phase on Rh/Ru substitution for x greater than or similar to 0.06. (C) 1999 Elsevier Science B.V. All rights reserved.
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Betancourth, D., V. F. Correa, and D. J. García. "Evidence of a Low Energy Anisotropy in GdCoIn_5." Journal of Low Temperature Physics 179, no. 1-2 (2015): 90–93.
Abstract: We investigate the effects of an applied magnetic field on the magnetic properties of the antiferromagnet GdCoIn 5 . The prominent anisotropy observed in the susceptibility below TN is rapidly suppressed by a field of just a few Tesla. Further evidence of this low energy-scale is obtained from magnetoresistance and magnetostriction experiments. The lattice length, particularly, shows a sudden change below 2 T when the magnetic field is applied perpendicular to the crystallographic c^ -axis.
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D'Anna, G., and Andr. "Flux-line response in 2H-NbSe2 investigated by means of the vibrating superconductor method." Physica C: Superconductivity and its applications 218, no. 1-2 (1993): 238–244.
Abstract: We measure transverse AC losses in the low- and high-amplitude regime of 2H-NbSe2 single crystals using vibrating superconductor methods. The measurements are sensitive to small deviations of the critical state. The data constitute evidence for a peak effect of the critical current as a function of the temperature in this compound. We construct in the H-T phase diagram the “peak-effect” line which is supposed to mark an abrupt cross-over in the vortex-pinning regime.
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Decca, R. S., H. D. Drew, B. Maiorov, J. Guimpel, and E. J. Osquiguil. "Inducing superconductivity at a nanoscale: Photodoping with a near- field scanning optical microscope." Journal of Microscopy 194, no. 2-3 (1999): 407–411.
Abstract: The local modification of an insulating GdBa2Cu3O6.5 thin film, made superconducting by illumination with a near-field scanning optical microscope (NSOM), is reported. A 100-nm aperture NSOM probe acts as a sub- wavelength light source of wavelength ?(exc)=480-650 nm, locally generating photocarriers in an otherwise insulating GdBa2-Cu3O6.5 thin film. Of the photogenerated electron-hole pairs, electrons are trapped in the crystallographic lattice, defining an electrostatic confining potential to enable the holes to move. Reflectance measurements at ? = 1.55 ?m at room temperature show that photocarriers can be induced and constrained to move on a ?? 200 nm scale for all investigated ?(exc). Photogenerated wires present a superconducting critical temperature T(c) = 12 K with a critical current density J(c) = 104 A cm-2. Exploiting the flexibility provided by photodoping through a NSOM probe, a junction was written by photodoping a wire with a narrow (? 50 nm) under-illuminated gap. The strong magnetic field modulation of the critical current provides a clear signature of the existence of a Josephson effect in the junction.
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