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Resume Objectifs La decouverte de pheochromocytome ou de paragangliome secretant au cours d’une grossesse est une situation rare et grave, engageant le pronostic maternofœtal. L’objectif de cette serie de cas est de discuter la prise en charge optimale de ces patientes pendant la grossesse. Methodes Il s’agit d’une etude retrospective des cas de pheochromocytome (n = 2) ou de paragangliome (n = 2) pris en charge au cours d’une grossesse au sein du Centre Hospitalier Universitaire (CHU) de Lille (France) entre 2013 et 2020. Resultats Nous rapportons quatre cas de patientes dont le diagnostic de pheochromocytome ou paragangliome a ete realise pendant la grossesse, a respectivement 4, 28, 31 et 34 semaines d’amenorrhee (SA). Leurs grossesses etaient marquees par un tableau brutal d’hypertension arterielle (HTA) parfois associe a des cephalees, des sueurs et des palpitations. Les patientes ont toutes accouche par cesarienne apres une preparation medicale par inhibiteurs calciques, avec une bonne issue. L’exerese de la tumeur s’est deroulee a distance de l’accouchement pour chaque patiente. Conclusions La strategie therapeutique repose sur un traitement medical par inhibiteurs calciques ou alphabloquants et un traitement curatif lie a l’âge gestationnel. La prise en charge multidisciplinaire ainsi que le diagnostic precoce permettent d’ameliorer le pronostic maternofœtal. La voie d’accouchement privilegiee est la cesarienne, mais peut se discuter. L’exerese se fera idealement a distance de l’accouchement. L’analyse de ces cas a permis l’elaboration d’un protocole de suivi et de prise en charge des patientes atteintes d’un pheochromocytome ou paragangliome lors de leur grossesse.

Objective To describe EEG patterns of critical Coronavirus Disease 2019 (COVID-19) patients with suspicion of encephalopathy and test their association with clinical outcome. Methods EEG after discontinuation of sedation in all patients, and somesthesic evoked potentials and brainstem auditive evoked potentials when EEG did not show reactivity, were performed. Clinical outcome was assessed at day 7 and 14 after neurophysiological explorations. Results 33 patients were included for analysis. We found slowed background activity in 85% of cases, unreactive activity in 42% of cases, low-voltage activity in 21% of cases and rhythmic or periodic delta waves in 61% of cases. EEG epileptic events were never recorded. Clinical outcome at day 14 was associated with unreactive background activity and tended to be associated with rhythmic or periodic delta waves and with low-voltage activity. Results of multimodal evoked potentials were in favor of a preservation of central nervous system somatosensory and auditory functions. Conclusions Among critical COVID-19 patients with abnormal arousal at discontinuation of sedation, EEG patterns consistent with encephalopathy are found and are predictive for short term clinical outcome. Significance The abnormal EEG with presence of periodic discharges and lack of reactivity could be related to encephalopathy linked to COVID-19.

Previous studies unveiled a relation between COVID-19 severity and obesity. The aims of this multicenter retrospective cohort study were to disentangle the association of body mass index (BMI) and associated metabolic risk factors, with pneumonia outcomes in critically ill patients with COVID-19, and explore the impact of age and sex on this relationship. Participants were COVID-19 patients admitted in intensive care in 21 centers in Europe, Israel, and USA, between 02/19/2020 and 05/19/2020. The exposure of interest was BMI. The primary and secondary outcomes were the need for invasive mechanical ventilation (IMV), and 28-day mortality. The covariates were age, sex, and diabetes, hypertension, hyperlipidemia, and current smoking. We enrolled 1,461 patients (median age 64 years (Interquartile range (IQR), 40.9-72.0); 73.2% males; median BMI 28.1 kg/m2 (IQR, 25.4-32.3); 1,080 patients (73.9%) required IMV and the 28-day mortality rate was 36.1% (95% confidence intervals (CI), 33.0-39.5). Adjusted mixed logistic regression model showed a significant relation between BMI and IMV: odds ratio 1.27 (95% CI, 1.12-1.45) per 5 kg/m2 in the whole cohort, and 1.65 (95% CI, 0.97-2.79) per 5 kg/m2 in females under 50 years. Adjusted Cox proportional hazards regression model showed a significant association between BMI and mortality, which was only increased in obesity class III (≥40 kg/m2) (Hazard Ratio 1.68 (95% CI 1.06-2.64). In conclusion, we observed in critically ill COVID-19 patients, a linear association between BMI and the need for IMV, independent of other metabolic risk factors, and more pronounced in younger females, and a non-linear association between BMI and mortality risk. Trial Registration: ClinicalTrials.gov Identifier: NCT04391738 Funding Statement: No specific funding. Declaration of Interests:The authors declared no conflict of interest. Ethics Approval Statement: The study complied with standard operating procedures in place, in accordance with the European Data Protection Directive (95/46/EC) and, upon its entry into force, Regulation (EU) 2016/679 (also referred to as the General Data Protection Regulation (GDPR)), and French CNIL frameworks n° MR004 regarding the processing of personal data in clinical studies. The institutional review board from other centers in USA and Israel approved the retrospective case series as minimal-risk research using data collected for routine clinical practice and waived the requirement for informed consent.

Background The French health authorities recommend systematic screening for Chlamydia trachomatis (Ct) urogenital infections in dedicated sexual health centers (planning centers) for women under 25 years old and for women who have changed partners during the last year. The two main purposes of this study were to assess adherence to this recommendation in planning centers and to identify possible obstacles to this screening. Methods We conducted an observational prospective study from April to August 2013 in planning centers of Poitou-Charentes. Data on declarative screening practices and possible obstacles to Ct screening were collected qualitatively. Real center practices were also recorded to assess conformity with guidelines. Quantitative data were collected about real activities in each center. Screening percentage among women younger than 25 years and among those who had changed partners during the year was computed for each center. The main endpoint was percentage of centers that did not follow the recommendations. Declared practices were compared to observational practices using real practices data. Results Twelve out of 17 planning centers in the region participated. Six centers declared they performed systematic screening for Ct infection in women under 25 and 2 centers in women who had changed partners during the year. No center fully complied with the recommendations. Forty-three percent (601/1390) of women with standard screening criteria were screened and 52 % (102/197) of women without these criteria were screened. Depending on the center, declared practices could overestimate or underestimate the observed practices. The declared obstacles were lack of time, patient refusal, budget issues and no specific organization. Conclusion Poitou-Charentes planning centers screen for Ct infection in women younger than 25 years old and those who have changed partners during the last year depending on risk factors (unprotected sex, infected partner…). Which patients need this screening has to be clarified.

Resume Introduction La maladie de Castleman multicentrique (MCM) peut mimer une maladie de Still de l’adulte. Elle est exceptionnellement associee a une anasarque, une microangiopathie thrombotique et une dysautonomie. Observation Nous rapportons l’observation d’une femme de 32 ans qui presentait a la fois une oligo-anurie avec anasarque, une microangiopathie thrombotique et un tableau compatible avec une maladie de Still. L’evolution etait initialement favorable sous corticotherapie, immunoglobulines polyvalentes et plasmaphereses, avec cependant la persistance de poussees marquees par un syndrome dysautonomique severe et une corticodependance. Le diagnostic de maladie de Castleman de type mixte, HHV8 et VIH negative, etait porte 4 ans apres le debut des symptomes sur une biopsie ganglionnaire. L’evolution etait initialement favorable apres l’introduction de tocilizumab associe a la corticotherapie, puis le remplacement du tocilizumab par l’anakinra permettait un controle durable de la maladie. Conclusion Le tableau de notre patiente correspond partiellement a la description du syndrome TAFRO (Thrombocytopenia, Anasarca, myeloFibrosis, Renal dysfunction, Organomegaly) variant de MCM recemment decrit chez des patients japonais.

Resume Introduction La grande majorite des myopericardites aigues est d’origine virale ou indeterminee. Observation Nous rapportons le cas d’une jeune patiente ayant presente deux tableaux cliniques rapproches compatibles avec le diagnostic d’infarctus du myocarde a coronaires saines, mais pour lesquels le diagnostic final reposant sur l’imagerie cardiaque par resonance magnetique et le serodiagnostic est celui de myopericardite a Chlamydia trachomatis . Une antibiotherapie par levofloxacine a permis d’obtenir une disparition definitive des symptomes. Conclusion L’infection a Chlamydia trachomatis , plus souvent cause d’infections genitales, de grossesse extra-uterine ou d’infertilite, se manifeste rarement par une myopericardite aigue. Son identification permet un traitement specifique.

Resume Le syndrome de Tako-tsubo ou ballonisation transitoire de l’apex du ventricule gauche (VG) est une entite de decouverte recente mimant un syndrome coronarien aigu (SCA) en l’absence de lesions coronaires significatives associees. Il concerne surtout les femmes âgees exposees a un stress intense. Sa physiopathologie precise est inconnue et son traitement reste empirique. Le pronostic est souvent favorable en dehors de complications aigues imprevisibles.

Resume Le HELLP syndrome associe une hemolyse, une elevation des enzymes hepatiques et une thrombopenie. Ce syndrome survient le plus souvent dans un contexte de dysgravidie et de preeclampsie. Le diagnostic et la prise en charge du HELLP syndrome font encore l'objet de controverses. Ainsi, afin d'ameliorer le pronostic fœtal sans majorer la morbidite maternelle, deux attitudes therapeutiques se discutent : interruption rapide de la grossesse avec risques de morbidite et mortalite fœtales lies a la prematurite ou traitement conservateur avec risques maternels, notamment a type de complications hemorragiques hepatiques et/ou cerebromeningees. La prise en charge therapeutique doit donc etre instauree apres evaluation de la balance benefices/risques pour la mere et l'enfant.

The psychosocial rehabilitation and the quality of life of schizophrenics have constituted the main concern in the taking care of these patients since their return into our society. Thus, the emergence of atypical neuroleptics allows us to imagine very interesting and important perspectives concerning these 2 concepts. The adaptation to social and professional life, and the quality of life have been rarely compared according to the antipsychotic therapeutic used (classical neuroleptics or atypical neuroleptics). As many authors underline it, there are still very few studies undertaken concerning this subject because of the diverse methodological and ethical limitations implied. That is why we established a transversal study of the psychosocial adaptation and of the quality of life of 2 stabilized schizophrenic groups. These 2 different groups are: the NC group under classical neuroleptics on the one hand, and the NA group under atypical neuroleptics on the other hand. The main target of this study is to observe the influence of the atypical neuroleptics independently of the other factors. Three evaluation scales were used: the PANSS, the psychosocial skill scale (EAPS) of G. Darcourt and the French translation by P. Martin of the Functional Statut Questionnaire (FSQ), and a collection of the clinical and therapeutic socio-demographic data. Concerning the psychosocial capacities, the total results revealed one significant difference (p-value

It is generally agreed that stress induced leakage current (SILC), in MOS devices, is due to electrons tunneling through stress-induced neutral traps and that SILC has a steady-state component. However, it was observed that SILC, created by positive or negative Fowler–Nordheim injection in 7 and 5 nm thick oxides, decays slowly but continuously when, after stress, the samples are positively or negatively biased at low voltage. The decay is irreversible as long as the gate voltage is less than 4 V. To explain the SILC decay, it has been proposed that some active traps in the tunneling process might possibly be deactivated. The present communication adds first complementary observations on this subject: it shows that the above phenomenon is observed in 3.8 and 3.5 nm thick oxides after a positive stress; that this phenomenon is stable as long as the temperature remains below the SILC annealing temperature threshold which is equal to 200°C; and that during the SILC decay the interface state density does not diminish and can even increase. This communication shows secondly that after a negative stress two SILC components exist in these thin oxides: one which has all the characteristics of the SILC induced by a positive stress and another which does not exist in thicker oxides, which does not decay when a low voltage is applied after stress and which is not annealed at 300°C.

In this paper, we present a full quantum model of metal oxide semiconductor capacitance based on a self-consistent resolution of Schrodinger and Poisson equations. The model is used in accumulation to extract the oxide thickness of N+ polycrystalline silicon–SiO2–P silicon capacitors in the range 2–5 nm. The extraction results are in agreement with reference ellipsometric measurements to

It is known that stress induced leakage current created by Fowler-Nordheim injection in Si/SiO2 structures has a component which increases drastically as the oxide thickness decreases. In the literature this component is considered to be a reproducible dc component. Nevertheless recent measurements have shown that this component decays continuously when a non-stressing field is applied on the sample. The decay is irreversible as long as the sample undergoes no further stressing. This paper reports complementary information about this phenomenon. The magnitude of the decay is studied as a function of the stress field polarity, the non-stressing field magnitude and polarity, and the measurement field polarity. Our conclusion is that the stress induced leakage current decay is triggered by holes of low energy injected from the anode.

The stress induced leakage current (SILC) in Si/SiO2 structures with thin gate oxides has a steady-state component which increases drastically when the oxide thickness decreases. It is generally agreed that the SILC is due to electron tunnelling trough stress-induced traps. However, it was observed that the SILC, created by Fowler–Nordheim injection, decays continuously when, after stress, the samples are positively or negatively biased at a low voltage. The decay is irreversible as long as the gate oxide is not biased at a high voltage. The present article adds complementary observations. It shows, first that the above phenomenon is observed in 3.5 nm thick oxides, secondly, that this phenomenon is stable as long as the temperature stays below 200°C, and thirdly, that during the SILC decay, the interface state density does not diminish.

Fowler–Nordheim tunneling injection was performed, from the substrate, in an n-channel metal-oxide-semiconductor field effect transistor with polycrystalline silicon gate. We explain the injection of hot holes in the oxide by an anode hole injection model. We compare behaviors of the anode hole current, the generated positive oxide charge, and the kinetics of interface state creation, according to the oxide thickness. We deduce two things from it: on one hand, mechanisms of interface state and oxide positive charge creation would be the same, and on the other hand, holes created at the anode would cause deterioration of the Si/SiO 2 interface.

Stress-induced leakage current (SILC) has several components. One of these components increases when the oxide thickness decreases. We show that this component can be reduced by application of a low field of opposite polarity to the stress field or by temperature annealing. When a positive charge is present in the oxide, this charge is also reduced. We show that these two effects are independent.

Low field leakage currents, through thin gate oxides of metal–oxide–semiconductor capacitors, increase after negative high field stress. We have observed that this increase could be reduced and even suppressed if the trapped holes created by the stress were neutralized by application of low voltage pulses. We have also observed that these pulses had the effect of making the recharge of the stress created slow states more and more difficult.

We report on first ISO observations of interstellar ices in the direction of the protostellar object RAFGL 7009S. Due to its extreme extinction this source represents a unique target for the detection of interstellar ices. Identified molecules include H2O, CO, and CO2together with13CO2, CH4, OCS, and H2CO. Other less firmly identified features are observed that appear in laboratory spectra of interstellar ice analogs. The evolution of interstellar dust grains plays an active role in interstellar chemistry and determines solid state and gas phase abundances. During their lifetime dust grains cycle between dense and diffuse clouds and undergo considerable metamorphism. Comets are likely the least evolved bodies in the Solar System and comet nuclei may be low density aggregates of interstellar dust. An important constraint for the origin and evolution of comets can be derived from the presence of pre-solar ices and organics. To study volatiles and grains in the cometary coma is one of the future goals of the ROSETTA comet rendezvous mission. In comparison with new ISO data we present laboratory studies on interstellar ice analogs which reveal the composition and structure of ices in dense molecular clouds. We discuss the ubiquitous presence and high abundances of interstellar CO2ice in the cometary context and estimate column densities of molecules such as CH4, H2CO, and OCS which provide important constraints on the origin of cometary ices and for cometary evolution.

Fowler-Nordheim tunneling injection was performed, from the substrate, in an n-channel metal-oxide-semiconductor field effect transistor with polysilicon gate. We observe the injection of hot holes in the oxide. We try to explain the injection of hot holes by the anode hole injection model. We show the hot hole injection decreases with the oxide thickness, and the hot hole injection efficiency is practically the same during a constant voltage stress. We attempt to link the evolution of the generated positive charge with the injected holes for three oxide thicknesses.

International audience; Stress Induced Leakage Currents (SILC) are studied in 5 nm-thick oxides on both capacitors and N-MOSFET's after homogeneous FOWLER-NORDHEIM injections under high field stress (

This work presents polarity effects during Fowler-Nordheim electric field stress on defect generation in thin silicon dioxide films and at the interface with the silicon. The results show a dissymmetry on interface state kinetic generation and the presence of a critical injected fluence at which the dissymmetry is reversed. For injected fluences lower than this critical charge, the density of interface states created under positive gate bias is higher than that generated under negative bias, and if the injected charge is higher than the critical fluence the dissymmetry is reserved. However, the net oxide positive charge generated under positive bias is always lower than that created under negative bias.

Fowler-Nordheim tunneling injections were performed, from the gate, or from the substrate, in P-type metal oxide semiconductor capacitors with polysilicon gates in both wet and dry oxides. When the injection was from the gate, trapped holes, as well as negative and anomalous positive charges were created and it was possible to determine their amplitude and their centroid. When the injection was from the substrate, only negative and anomalous positive charges were created, but the determination of the centroids was not always possible since the positive charge appears to be located at both interfaces.

In this work, the effects of the degradation generated by homogeneous hot-electron injection in a one-dimensional model of current-voltage characteristics for short-channel MOSFETs are introduced. A distributed charge model, implemented in the SABER simulator is used. Simulation results obtained for n-MOS transistors demonstrate good agreement with the experimental data for interface state density inferior to 3 × 10 11 cm −2 eV −1 . The samples are degraded by homogeneous electron photoinjection and the interface trap density is performed by the pumping charge method.

The oxide positive charge and the interface-state formation caused by a negative gate bias in a polycrystalline silicon gate-oxide-semiconductor capacitor versus injecting temperature in the range of 77–400 K is studied. It is found that the generation of both interface-states and oxide charge is temperature independent which indicates that the motion of each mobile species (as the hydrogen-related species) must be excluded. The formation of interface-states is linked to the break of SiSi or SiO distorted bonds at the Si SiO 2 interface, and the generation of the oxide positive charge to the electron-emission from pre-existing or created neutral traps.

We have studied the time decay of the positive charge induced into a 12 nm thick oxide of MOS capacitors by Fowler-Nordheim tunnel injection. We show that this charge isdue to trapped holes and that at the same time neutral traps are induced. We underline the similarity of the above decay with the time dependence observed in luminescence decay and dielectric depolarization which is supposed to be due to a many body process.

Skeletal muscle atrophy is common, debilitating and without acceptable treatment options. In humans, skeletal muscle atrophy occurs under various physiological and disease conditions, such as injury resulting in immobilization, critical illness, burns, cancer, COPD, liver disease, AIDS, congestive heart failure, diabetes. The reduction in strength and endurance associated with the involuntary loss of muscle mass results in functional limitations, loss of independence, reduced quality of life, increased disability, and increased mortality. Selective β2 adrenoceptor agonists, such as formoterol, elicit skeletal muscle hypertrophy, which is associated with increased force producing capacity in both fast- and slow-twitch muscles. Hypertrophy can be blocked by selective β2 adrenoceptor antagonist or genetic deletion of the β2 adrenoceptor. Several studies have shown potential efficacy of β2 adrenoceptor agonists in addressing muscle wasting in many animal species and humans. In this report, the effect of formoterol against a rodent model of muscle disuse atrophy was evaluated. The disuse atrophy was induced by cuff crushing-based nerve injury which is leading to neuropathic pain and eventually muscle disuse. It is known that selective β2 adrenoceptor agonists are effective against neuropathic pain, although the effect on muscle atrophy and function has not been evaluated yet. Therefore, formoterol was tested in this model in both prevention and therapeutic modes. The disuse atrophy was significantly prevented, and recovery from the atrophy was also significantly promoted by the formoterol treatment. In conclusion, formoterol is effective in the nerve injury-induced muscle disuse atrophy, and selective β2 adrenoceptor agonists might be a potential therapeutic option for treating muscle atrophy conditions caused by disuse and immobilization due to injury and critical illness.

Introduction L’allogreffe intraportale d’ilots permet la restauration d’une insulino-secretion. Les resultats sont cependant oberee par une intense activation de la coagulation et de l’inflammation, favorisant la destruction initiale des ilots. Celle-ci n’est pas maitrisee par l’heparine, mais reduite par l’antithrombine sur un modele animal. L’objectif de cette etude etait d’optimiser la fonction primaire du greffon, en utilisant l’antithrombine. Patients et methodes Sept patients, presentant un diabete insulinoprive instable ont ete inclus dans cet essai de phase 1 d’allogreffe intra-portale apres catheterisme chirurgical. Chaque patient devait recevoir 1 a 2 injections d’ilots sur 2 mois sous une immunosuppression de type Edmonton, associee a 150 U/Kg d’antithrombine III recombinante (Aclotine * ) les 2 heures precedant et suivant la greffe, afin de maintenir un taux d’antithrombine entre 250 % et 300 %. L’objectif etait d’obtenir un β score > 6 un mois apres la 2 e greffe, avec possibilite de 3 e greffe en cas d’echec, Resultats Cinq patients ont ete greffes. Deux thromboses portes partielles asymptomatiques, l’une lors de la 1re greffe empechant leur poursuite, l’autre a la 3 e greffe, ont justifie une anticoagulation prolongee. Un syndrome hemorragique a necessite la transfusion de 2 culots. Le β-score 1 mois apres la 2 e greffe n’etait > 6 chez aucun patient, justifiant une 3 e greffe, hormis chez celui ayant presente la thrombose initiale. Les 4 patients ayant recu 3 injections d’ilots sur une periode de 4 a 7 mois ont arrete l’insuline 1 a 4 mois apres la 3 e greffe et demeuraient insulino-independants avec HbA1c Conclusion Cet essai a ete interrompu au 5 e patient en raison d’une absence de superiorite de l’antithrombine comparee a l’heparine, avec 3 effets secondaires graves, heureusement resolutifs, sur 13 injections. Les 4 patients ayant recu 3 greffes restent insulino-independants.

Resume Introduction We previously reported that serum levels of endocan, an endothelial derived dermatan sulphate proteoglycan which regulates LFA-1/ ICAM-1 interactions in vitro , are elevated in patients with sepsis. As the endothelium is an important player in sepsis, and endothelial activation parallel sepsis severity, we wonder if blood levels of endocan could be used as a diagnostic and prognostic marker in sepsis and how it compares with previously pro-posed markers as von Willebrand factor, IL6, IL 10, Procalcitonin or C reactive protein. We also studied kinetics of endocan secretion by endothelial cells in vitro after stimulation by soluble mediators involved in sepsis. Material and methods Endocan values were quantified by an in house sandwich type ELISA. Commercial assays were used for procalcitonin, C reactive protein, IL10, IL6, von Willebrand Factor. Design Prospective observational study. Setting Intensive care unit (ICU) of the University Hospitals of Lille, France, and Geneva, Switzerland. Patients All patients admitted to the intensive care unit over a 6-month period with clinical evidence of sepsis. Interventions None. Measurements and main results In vitro , we showed a sustained endocan secretion by endothelial cells after stimulation by LPS and TNFα. Circulating levels of endocan measured in 63 patients admitted in ICU with sepsis were significantly elevated compared to 20 healthy donors and 7 SIRS patients: 2.71 ± 4.88 ng/ml vs 0.77 ± 0.44 ng/ml vs 0.68 ± 1.03 ng/ml (median ± interquartile range) (p Conclusions These results suggest that in septic patients, endocan blood level is related to the severity and to the outcome of the patients, and may represent a novel endothelial cell dysfunction marker.

High electrical stresses have been applied to n -MOS capacitors prepared following two thermal oxidation methods. The increase of the interface state density was investigated by means of a conductance method and incidentally by a quasi-static method. A threshold effect, possibly related to a Fowler-Nordheim injection, has been found in the increase of this density versus field stress. At high field stresses, a second conductance peak has been observed, which can be explained in terms of new interface states, rather than lateral nonuniformities.

Thin gold-silicon monoxide-gold films have been prepared by thermal evaporation in vacuo; the oxide thickness was about 5000 A, with composition SiOx (x slightly greater than one). A study of capacity and loss tangent as functions of frequency and temperature was carried out. The experimental results agree approximately with the Simmons model (established for alternating current). They show the existence of Schottky barriers of approximately 70 A thickness. The conduction in the interior of the insulator is ascribed to a Poole-Frenkel effect with activation energy 0.45 eV; the concentration of donor centres has been found to be about 2×1019 cm-3.

The dielectric properties of 16 samples of evaporated silicon oxide sandwiched between gold electrodes and annealed at various temperatures were investigated in the range 10-1-105 Hz. At high frequencies and low temperatures the real and imaginary parts of the complex dielectric susceptibility of all the samples obey the relation χ′(ω) ∝ χ″(ω) ∝ ωs−1 with S ⩾ 0.6; this is the power law which is often observed in dielectrics. At low frequencies three different types of behaviour were observed. For five samples χ′ and χ″ obey a second law χ′(ω) ∝ χ″(ω) ∝ ωs1−1 with S1

Thermally stimulated currents in evaporated silicon oxide films were studied below 383 K. The experimental results showed one or two peaks. The low temperature peak can be attributed to the polarization of the bulk of the specimen. The activation energy corresponding to this peak is very similar to the a.c. activation energy. The high temperature peak cannot be attributed to a volume effect. It could indicate the existence of a space charge due to a thin zone which has a conductivity lower than that of the bulk of the specimen.

Resume Le courant photoelectrique interne a ete etudie, en fonction de l'energie des photons incidents et de la tension de polarisation appliquee a l'echantillon, pour des structures AlSiOAu ayant comme epaisseurs: aluminium 1000 A, SiO de 500 a 2000 A, Au 150 A. Les resultats obtenus concordent avec l'hypothese suivant laquelle les photoelectrons seraient issus des electrodes metalliques; ces photoelectrons subissant ensuite des interactions avec les phonons dans le SiO. L'interpretation est faite sur la base d'un effet Schottky plutot que sur celle d'un effet Poole-Frenkel. Le libre parcours moyen de l'interaction electron-phonon a ete trouveegal a 5,8 A. Les hauteurs de barriere de potentiel, aux interfaces AlSiO et AuSiO, determinees par le diagramme de Fowler, sont de 2 eV environ.

Resume Les caracteristiques courant-tension ont ete etudiees pour des structures Al-SiO-Au; les epaisseurs d'oxyde etaient inferieures a 2000 A. Il est montre que la conduction peut s'expliquer en supposant un effet Poole-Frenkel a trois dimensions applique a un modele d'isolant contenant des niveaux donneurs et des niveaux pieges.