Thermal behavior Spice study of 6H-SiC NMOS transistors

International audienc

Thermal behaviour of 6H–SiC bipolar transistors: spice simulation and applications

International audienc

Mesures de la durée de vie des porteurs, dans la base et l'émetteur de cellules solaires au silicium, à partir des photoréponses transitoires à une impulsion laser

Carrier lifetime measurements from the short-circuit photocurrent i(t) decay and both the decay and increase of open-circuit photovoltage v co(t) are studied by taking into account the conditions of the pulse excitation (duration, wavelength, intensity) and the solar cell properties (base width, back contact, emitter doping profile, p-n junction currents). The theoretical analysis and conditions of validity of the above measurement methods are compared with the experimental results obtained with N+ P cells of W = 350 and 450 μm base width submitted to laser pulses of 2 and 60 ns. When using penetrating 1.06 μm pulses, the i(t) decay gives the values and variations with carrier injection level of carrier bulk lifetime and/or effective lifetime in the cell base. The i*( t) response to strongly absorbed 0.53 μm pulse lead to the operative carrier lifetime in the cell emitter and show the influences that the doping profile may have. An approximated value of the latter lifetime may be deduced from the vco(t) increase whatever the pulse wavelength used. But injection conditions at the junction p-n and temporary trapping phenomena narrow the conditions for which the voltage v co(t) decay gives a measurement of the minority carrier lifetime in the cell base.Les possibilités des méthodes de mesure de durée de vie, reposant sur la décroissance des photocourants de court-circuit i(t) et à la fois sur la croissance et la décroissance des phototensions de circuit ouvert vco(t), sont étudiées en fonction des conditions d'excitation (durée, longueur d'onde, densité de porteurs excités) et des propriétés des cellules solaires (dimensions, nature des contacts, profil des dopages, courants à la jonction p-n). L'analyse des conditions de validité de ces méthodes est confrontée aux résultats expérimentaux obtenus avec des échantillons de type N+ P (d'épaisseur de base 350-450 μm) soumis à des impulsions laser de 2 à 60 ns de durée. L'étude montre que, pour λ = 1,06 μm, à la fois la durée de vie volumique et la durée de vie effective des porteurs minoritaires de la base, et leur évolution avec le niveau des porteurs, sont fournies par les réponses i(t). Pour λ = 0,53 μm, les réponses i*(t ) donnent accès à la durée de vie opérationnelle des porteurs minoritaires créés dans l'émetteur et montrent l'influence des profils de dopage sur cette durée de vie. Une valeur approchée de cette même durée de vie est également fournie par la croissance des signaux vco(t), quelle que soit la longueur d'onde λ utilisée. Les conditions d'injection au niveau de la jonction p-n et les phénomènes de piégeages temporaires limitent par contre les conditions sous lesquelles la décroissance des tensions transitoires peut donner la durée de vie des porteurs minoritaires dans la base

BSIM3v3 характеристика та моделювання транзисторів MOS Si1 – xGex за 130 нм субмікронною технологією

Перспективи та доцільність роботи представлені для транзисторів MOSi1 – xGex змодельованих за 130 нм субмікронною технологією. Модель BSIM3v3 використовувалася для аналізу роботи транзисторів відповідно до вивчення впливу фракції x германію (з x = 0 до x = 1) на електричні характеристики цих транзисторів з урахуванням впливу температури. PSpice параметри двох різних транзисторів NMOSi1 – xGex і PMOSi1 – xGex були розраховані і використані у моделюванні. Вихідні і перехідні електричні характеристики були визначені в інтервалі температур від – 200 до 200 °С. Субпороговий режим також розглядався шляхом обчислення струмів ION та IOFF як функції VGS для постійного VDD. Результати моделювання показують, що вищезгадані транзистори працюють належним чином у режимі з пороговою напругою близько 1.2 В. Вони можуть бути використані в мікроелектроніці низької напруги та малої потужності шляхом керування фракцією x германію.A prospective of work and a feasibility study are undertaken on MOSi1 – xGex transistors with a 130 nm submicron technology. BSIM3v3 model has been used to analyze the transistors’ operation, according to the study of the effect of Germanium fraction x (x = 0 to x = 1) on electrical performance of these transistors taking into account the influence of temperature. PSpice parameters of two different transistors NMOS1 – xGex and PMOS1 – xGex have been calculated and used in the modeling. The output and transfer electrical characteristics have been determined in the temperature range – 200 to 200 °C. The regime subthreshold was also addressed by calculating ION and IOFF currents as a function of VGS for constant VDD. Simulation results show that the above transistors work properly in a regime under a threshold voltage of about 1.2 V. They can be used in low voltage and low power microelectronics by controlling the germanium x fraction

Tolosa-hunt syndrome in children

We report a case of Tolosa-Hunt syndrome in a 4-year-old girl. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) revealed a left cavernous sinus involvement with internal carotid artery occlusion. Clinical signs included left ophthalmoplegia, convulsions and right hemiplegia. Etiopathogenesis of this syndrome is unclear but as in our case, response to corticosteroid therapy is spectacular and avoids unnecessary invasive diagnostic procedures. We underline the importance of cross-sectional imaging in the diagnostic approach. Several other diseases including tumors, vascular lesions and infections can have a similar clinical and/or imaging presentation. However, closely monitored evolution on imaging proves to be decisive in the establishment of final diagnosis of this syndrome

European phase II study of rituximab (chimeric anti-CD20 monoclonal antibody) for patients with newly diagnosed mantle-cell lymphoma and previously treated mantle-cell lymphoma, immunocytoma, and small B-cell lymphocytic lymphoma

PURPOSE: Mantle-cell lymphoma (MCL), immunocytoma (IMC), and small B-cell lymphocytic lymphoma (SLL) are B-cell malignancies that express CD20 and are incurable with standard therapy. A multicenter phase II study was conducted to assess the toxicity and the overall response rates (RR) and complete response (CR) rates to rituximab (chimeric anti-CD20 monoclonal antibody). PATIENTS AND METHODS: Between January 1997 and January 1998, 131 patients with newly diagnosed MCL (MCL1; n = 34) and previously treated MCL (MCL2; n = 40), IMC (n = 28), and SLL (n = 29) received rituximab 375 mg/m(2)/wk for 4 weeks via intravenous infusion. Restaging studies were performed 1 and 2 months after treatment. An analysis of the duration of response was conducted in December 1998. RESULTS: Eleven patients were unassessable, including one who died of splenic rupture after the first infusion. The RR among the 120 assessable patients was 30% (36 of 120 patients). The RR by histology was as follows: MCL1, 38%; MCL2, 37%; IMC, 28%; and SLL, 14%. Ten patients, all with MCL, achieved CR. The median duration of response in MCL was 1.2 years. Immediate side effects were common and usually responded to adjustments in the infusion rate. There were 31 episodes of infection after treatment; most cases were mild. Cardiac arrhythmia and ophthalmologic side effects occurred in 10 and nine patients, respectively, including one case of severe loss of visual acuity. CONCLUSION: Single-agent rituximab has moderate activity in MCL and IMC but only limited activity in SLL. The duration of response in MCL was similar to that previously reported in follicular lymphoma. Its use in combination with cytotoxic chemotherapy to increase the CR rate is warranted in MCL and IMC