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Chapelle A.,EAMEA | Authier N.,CEA Valduc Center for Nuclear Studies | Casoli P.,CEA Valduc Center for Nuclear Studies | Richard B.,French Atomic Energy Commission | And 4 more authors.
IEEE Transactions on Nuclear Science | Year: 2014

The aim of the experiments concerning neutron noise measurements presented in this article is to provide robust experimental subcritical data. These measurements will make possible to compare measured parameters to simulated ones. The results of these measurements must therefore be very accurate, with controlled uncertainties. To determine the relative contribution of uncertainties to the final result, a table presents the prompt multiplication estimated by a French team and a U.S. team. The different sources of uncertainties are then explored, by a sensitivity analysis, separated in three categories, linked to the experimental configuration, to the detection process and finally to the analysis process. These experiments improve the safety task of reactivity control far from criticality, with static methods, and the knowledge of the behaviour of a subcritical reactor. © 2014 IEEE.

Petitdidier S.,Normandie University | Berthet F.,Normandie University | Guhel Y.,Normandie University | Trolet J.L.,EAMEA | And 3 more authors.
Microelectronics Reliability | Year: 2015

This paper shows the influence of pre-existing electrical traps on the reliability of AlInN/GaN HEMTs by using simple methods. So, a kink effect has been highlighted by studying the impact of the illumination and the bias conditions on the electrical characteristics of the AlInN/GaN devices. Then, these devices have been electrically stressed for 216 h under three different bias conditions such as Off-state stress, On-state stress, and Negative Gate Bias (NGB) stress. All these electrical stresses induce a decrease in drain current and an increase in access resistance. However, the degradation of the drain current and the access resistances are more important after an On-state stress than an Off-state stress than a NGB stress. We have highlighted that the three different stresses induce more acceptor than donor traps in AlInN/GaN devices. The degradation of the electrical properties of stressed devices seems irreversible. Moreover, an evolution of the kink effect has been observed after the three ageing tests. To our knowledge, it is the first time that the impact of the pre-existing electrical traps on the degradation mechanism induced by On-state, Off-state and NGB stresses is carried out on AlInN/GaN devices. © 2015 Elsevier Ltd.

Manduci L.,EAMEA | Tenailleau L.,GEA | Trolet J.L.,EAMEA | De Vismes A.,EAMEA | And 3 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using γ spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors. © 2009 Elsevier B.V. All rights reserved.

Berthet F.,University of Caen Lower Normandy | Guhel Y.,University of Caen Lower Normandy | Gualous H.,University of Caen Lower Normandy | Boudart B.,University of Caen Lower Normandy | And 3 more authors.
Microelectronics Reliability | Year: 2011

We report on the non-invasive measurements of the temperature in active AlGaN/GaN HEMTs grown on sapphire substrate during an electrical stress. The original study permits to highlight the drop of the self-heating in operando during the electrical stress by using Raman spectroscopy. Moreover, a correlation between the decrease of the self-heating and the fall of the drain current during the stress has been demonstrated. This study also highlights that the self-heating of the components and the influence of the ageing test on the self-heating are clearly linked to the position where temperature measurements are carried out. © 2011 Published by Elsevier Ltd. All rights reserved.

Guhel Y.,University of Caen Lower Normandy | Boudart B.,University of Caen Lower Normandy | Gaquiere C.,British Petroleum | Vellas N.,MC2 | And 2 more authors.
Electronics Letters | Year: 2010

An original method is presented to improve DC electrical performance of AlGaAs/InGaAs PHEMTs by using a low neutron radiation dose. An increase of the drain-source saturation current, a decrease of the knee voltage and a reduction of the leakage current of the Schottky contact are observed without degrading the current-gain cutoff frequency when the devices are irradiated with a neutron radiation dose of 1.2×1010 neutrons/cm2. © 2010 The Institution of Engineering and Technology.

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