Impact of Gamma Radiation on Dynamic RDSON Characteristics in AlGaN/GaN Power HEMTs

GaN high-electron-mobility transistors (HEMTs) are promising next-generation devices in the power electronics field which can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters, where high frequencies and voltages are also needed. Its wide band gap (WBG), large breakdown electric field, and thermal stability improve actual silicon performances. However, at the moment, GaN HEMT technology suffers from some reliability issues, one of the more relevant of which is the dynamic on-state resistance (RON_dyn) regarding power switching converter applications. In this study, we focused on the drain-to-source on-resistance (RDSON) characteristics under 60Co gamma radiation of two different commercial power GaN HEMT structures. Different bias conditions were applied to both structures during irradiation and some static measurements, such as threshold voltage and leakage currents, were performed. Additionally, dynamic resistance was measured to obtain practical information about device trapping under radiation during switching mode, and how trapping in the device is affected by gamma radiation. The experimental results showed a high dependence on the HEMT structure and the bias condition applied during irradiation. Specifically, a free current collapse structure showed great stability until 3.7 Mrad(Si), unlike the other structure tested, which showed high degradation of the parameters measured. The changes were demonstrated to be due to trapping effects generated or enhanced by gamma radiation. These new results obtained about RON_dyn will help elucidate trap behaviors in switching transistors

On the Entropy of Oscillator-Based True Random Number Generators under Ionizing Radiation

The effects of ionizing radiation on field-programmable gate arrays (FPGAs) have been investigated in depth during the last decades. The impact of these effects is typically evaluated on implementations which have a deterministic behavior. In this article, two well-known true-random number generators (TRNGs) based on sampling jittery signals have been exposed to a Co-60 radiation source as in the standard tests for space conditions. The effects of the accumulated dose on these TRNGs, an in particular, its repercussion over their randomness quality (e.g., entropy or linear complexity), have been evaluated by using two National Institute of Standards and Technology (NIST) statistical test suites. The obtained results clearly show how the degradation of the statistical properties of these TRNGs increases with the accumulated dose. It is also notable that the deterioration of the TRNG (non-deterministic component) appears before that the degradation of the deterministic elements in the FPGA, which compromises the integrated circuit lifetime.Ministerio de Economía y Competitividad (ESP-2015-68245-C4-1-P)Ministerio de Economía y Competitividad (ESP-2015-68245-C4-4-P)Ministerio de Economía y Empresa (TIN2016-79095-C2-2-R)CAM (S2013/ICE-3095

Sustainable Development Goal No. 12: Sustainable Consumption and Production. Study on student’s consumption habits.

La consecución del Objetivo de Desarrollo Sostenible nº 12 recogido en la Agenda 2030 de las Naciones Unidas supone la transición hacia pautas de consumo más sostenibles. El papel de la educación es clave para promover reflexión e inspirar hábitos de consumo que impliquen cambios relevantes en la manera en que usamos los recursos. En este sentido, resulta clave la formación inicial de los maestros, ya que éstos, serán un referente para la sociedad y los responsables de la formación escolar de los futuros profesionales. Así pues, el objetivo de este trabajo fue la realización de un diagnóstico sobre los hábitos de consumo de nuestros estudiantes, futuros maestros de Educación Primaria (GEP), a fin de poder desarrollar, en un futuro, un programa formativo que incida, especialmente, en los puntos más débiles detectados.The achievement of Sustainable Development Objective No. 12 included in the 2030 Agenda of the United Nations means the transition towards more sustainable patterns of consumption. The role of education is essential to promote reflection and inspire consumption habits that induce relevant changes on the way to using resources. In this sense, the initial training of teachers is a key issue; they will be a reference for society and those responsible for the school training of future professionals. Therefore, the objective of this work was to make a diagnosis about the consumption habits of our students, future teachers of Primary Education (GEP), in order to develop, in the future, a training program that influence, especially, the weakest points detected

Total Ionizing Dose Effects on a Delay-Based Physical Unclonable Function Implemented in FPGAs

Physical Unclonable Functions (PUFs) are hardware security primitives that are increasingly being used for authentication and key generation in ICs and FPGAs. For space systems, they are a promising approach to meet the needs for secure communications at low cost. To this purpose, it is essential to determine if they are reliable in the space radiation environment. In this work we evaluate the Total Ionizing Dose effects on a delay-based PUF implemented in SRAM-FPGA, namely a Ring Oscillator PUF. Several major quality metrics have been used to analyze the evolution of the PUF response with the total ionizing dose. Experimental results demonstrate that total ionizing dose has a perceptible effect on the quality of the PUF response, but it could still be used for space applications by making some appropriate corrections.Ministerio de Economía y Competitividad ESP2015-68245-C4-1-P, ESP-2015-68245-C4-4-P

Analysis of Kernel Redundancy for Soft Error Mitigation on Embedded GPUs

The use of state-of-the-art commercial processors such as graphical processing units (GPUs) is becoming increasingly common in the New Space industry in order to ensure high performance and power efficiency. However, commercial GPUs are not designed to operate in a harsh environment and therefore different protection techniques need to be applied to mitigate the effects of radiation, including those produced by single events. This paper assesses the effectiveness of redundant kernel execution on tightly constrained embedded GPUs under proton irradiation, with results suggesting a significant improvement in the SDC cross-section without penalizing the stability of the whole system. In addition, the posterior error analysis shows that the CPU is the source of the majority of the events, which are mainly dominated by functional interrupts.This work has been supported by the Spanish Ministry of Science and Innovation as part of the PID2019-106455GB-C22 project

Empirical Mathematical Model of Microprocessor Sensitivity and Early Prediction to Proton and Neutron Radiation-Induced Soft Errors

A mathematical model is described to predict microprocessor fault tolerance under radiation. The model is empirically trained by combining data from simulated fault-injection campaigns and radiation experiments, both with protons (at the National Center of Accelerators (CNA) facilities, Seville, Spain) and neutrons [at the Los Alamos Neutron Science Center (LANSCE) Weapons Neutron Research Facility at Los Alamos, USA]. The sensitivity to soft errors of different blocks of commercial processors is identified to estimate the reliability of a set of programs that had previously been optimized, hardened, or both. The results showed a standard error under 0.1, in the case of the Advanced RISC Machines (ARM) processor, and 0.12, in the case of the MSP430 microcontroller.This work was supported in part by Spanish MINECO under Project ESP-2015-68245-C4-3-P and Project ESP-2015-68245-C4-4-P

Radiation Testing of a Multiprocessor Macrosynchronized Lockstep Architecture With FreeRTOS

Nowadays, high-performance microprocessors are demanded in many fields, including those with high-reliability requirements. Commercial microprocessors present a good tradeoff between cost, size, and performance, albeit they must be adapted to satisfy the reliability requirements when they are used in harsh environments. This work presents a high-end multiprocessor hardened with macrosynchronized lockstep and additional protections. A commercial dual-core Advanced RISC Machine (ARM) cortex A9 has been used as a case study and a complete hardened system has been developed. Evaluation of the proposed hardened system has been accomplished with exhaustive fault injection campaigns and proton irradiation. The hardening approach has been accomplished for both baremetal applications and operating system (OS)-based. The hardened system has demonstrated high reliability in all performed experiments with error coverage up to 99.3% in the irradiation experiments. Experimental irradiation results demonstrate a cross-sectional reduction of two orders of magnitude.This work was supported in part by the Spanish Ministry of Science and Innovation under Project PID2019-106455GB-C21 and in part by the Community of Madrid under Project 49.520608.9.18Publicad

A view of the implanted SiC damage by Rutherford backscattering spectroscopy, spectroscopic ellipsometry, and transmission electron microscopy

4H-SiC single crystalline substrates were implanted at room temperature with 150 keV Al+ ions using fluences of 4 1014, 1 1015, and 2 1015 cm−2 with current density of 2.5 A cm−2. The samples were subsequently annealed at 1100 °C in N2 for 1 h in order to analyze their structural recovery. The disorder induced in both sublattices by the Al+ ions was studied by backscattering spectrometry in channeling geometry with a 3.5 MeV He2+ beam. The results were compared with the optical properties of the samples measured by spectroscopic ellipsometry. In a previous work, we concluded that during the postimplantation annealing of a highly damaged SiC crystalline material the short distance order can be recovered, while the long distance disorder remains. We also presented the possibility to have grains of different polytypes oriented faraway from the original direction. Now, this alternative is confirmed by the cross-sectional transmission and high resolution electron microscopy studies, carried out to obtain information about the crystal structure.Ministerio de Cienncias y Tecnología español-MAT2002-02843 (70% de fondos FEDER)Acuerdo de Colaboración Científica Húngaro-Españo-lE27 / 2001Fondo de Investigaciones Científicas de Hungría (OTKA)-T032029, T047011, T043704 y K6172

On the applications of IBA techniques to biological samples analysis: PIXE and RBS

The analyticaltechniques based on ion beamsorIBA techniquesgive quantitativeinformationonelemental concentrationin samples of awide variety of nature. In this work, weinformation on elemental concentrationin samples of awide variety of nature. In this work, weinformation on elemental concentrationin samples of awide variety of nature. In this work, weinformation on elemental concentrationin samples of awide variety of nature. In this work, wefocus on PIXE technique,analyzingthick target biologicalspecimens (TTPIXE),using 3MeVfocus on PIXE technique,analyzingthick target biologicalspecimens (TTPIXE),using 3MeVfocus on PIXE technique,analyzingthick target biologicalspecimens (TTPIXE),using 3MeVfocus on PIXE technique,analyzingthick target biologicalspecimens (TTPIXE),using 3MeVprotons producedby an electrostaticaccelerator.Anuclear microprobewas used performingprotons producedby an electrostaticaccelerator.Anuclear microprobewas used performingprotons producedby an electrostaticaccelerator.Anuclear microprobewas used performingprotons producedby an electrostaticaccelerator.Anuclear microprobewas used performingPIXEandRBSsimultaneously,inordertosolvetheuncertaintiesproducedintheabsolutePIXEPIXEandRBSsimultaneously,inordertosolvetheuncertaintiesproducedintheabsolutePIXEPIXEandRBSsimultaneously,inordertosolvetheuncertaintiesproducedintheabsolutePIXEPIXEandRBSsimultaneously,inordertosolvetheuncertaintiesproducedintheabsolutePIXEquantifying. Theadvantages of using both techniquesand anuclear microprobearediscussed.quantifying.Theadvantages of using both techniquesand anuclear microprobearediscussed.quantifying.Theadvantages of using both techniquesand anuclear microprobearediscussed.quantifying.Theadvantages of using both techniquesand anuclear microprobearediscussed.Quantitative resultsare shown to illustrate themultielemental resolutionof the PIXE technique;Quantitativeresults are shown to illustrate themultielemental resolutionof the PIXE technique;Quantitativeresults are shown to illustrate themultielemental resolutionof the PIXE technique;Quantitativeresults are shown to illustrate themultielemental resolutionof the PIXE technique;forthis,abloodstandardwasused.forthis,abloodstandardwasused.forthis,abloodstandardwasused.forthis,abloodstandardwasused

All chemical YBa2Cu3O7 superconducting multilayers: Critical role of CeO2 cap layer flatness

New advances toward microstructural improvement of epitaxial Ce0 2 films grown by chemical solution deposition and their use as buffer layers for YBa2Cu3O7 (YBCO) films are presented. We demonstrate that the degree of epitaxy and the fraction of (001) atomically flat surface area are controlled by the incorporation of tetravalent (Zr4+) or trivalent (Gd3+) cations into the ceria lattice. The degree of epitaxy has been investigated by means of Rutherford backscattering spectroscopy-channeling and reflection high-energy electron diffraction. In addition, we use a new methodology to quantify the fraction of (001) atomically flat area from atomic force microscopy images. Results are further correlated with the superconducting properties, microstructure, and texture of YBCO films grown by the trifluoroacetate route. A comparison with pulsed laser deposition and YBCO films grown on the same ceria layers is also presented. This growth procedure has allowed us to obtain all chemical multilayer films with controlled microstructure and critical current densities above 4 MA cm-2 at 77 K. © 2009 Materials Research Society.We acknowledge the financial support from MEC (MAT2005-02047, and CONSOLIDER NANOSELECT), Generalitat de Catalunya (Catalan Pla de Recerca SGR-0029 and CeRMAE), EU (HIPERCHEM, NMP4-CT2005-516858). J. Gàzquez, M. Coll, and A. Pomar are grateful to Spanish Ministery of Educacion y Ciencia (MEC) for financial support through Formacion de Personal Investigador (FPI), Formacion de Profesorado Universitario (FPU), and “Ramón y Cajal” programs.Peer Reviewe