Jean-Pierre Charles

Use of electrical stress and isochronal annealing on power MOSFETs in order to characterize the effects of 60Co irradiation

Abstract Fowler-Nordheim injection and isochronal anneals for several power MUM of various manufacturers made it possible to highlight that characteristic charge trap temperatures were identical to those due to radiation with 60 Co source. Results allow us to put forward some assumptions about electrical stress use as a selection component method for radiation environment.

Efficiency of magnetic coupled boost DC-DC converters mainly dedicated to renewable energy systems: influence of the coupling factor

Summary This paper presents a specific analysis of an individual basic magnetically coupled direct current-to-direct current (DC–DC) converter specially designed for integration in a distributed architecture of renewable energy generators for smart grid applications. In such distributed architecture dedicated for renewable energy, parallel high-voltage DC presents many advantages over the classical centralized one. We show that in such setup, high voltage can be advantageously produced using a specific magnetically coupled boost converter, and we point out the influence of the coupling factor, generally considered equal to one, on the overall performance of the converter and on the global energy efficiency of the installation. In this study, the generalized concepts of system energy parameters of DC–DC converters are introduced and applied to the transient analysis. Consequently, the operation of a magnetic coupled DC–DC converter with a recovery stage is modeled. The simulation results are compared with those of the behavioral study, deduced from the model pointing out the large influence of the coupling factor value on the global behavior and mainly on the value of the recovery voltage, in all the various parts of the switching cycle. The renewable energy generator operating parameters, such as current and voltage values, can then be predicted in a more useful way to compute new similar DC–DC converter systems. Copyright

R dson behavior in various MOSFET families

MOSFET are widely used for energy conversion and are must appropriated to photovoltaic systems up to 200VDC. Efficiency of these systems is very critical point. Efficiency of converters is mainly related to losses of its components and the MOSFET appears as one the main original. for the conversion of energy, it is very important to insure the higher efficiency as possible. In a first approach we studied MOSFET used in a switching mode. The losses in the transistor are directly linked to the Rdson value. As anterior studies have shown a linear dependence between the Rdson and the voltage supported by the transistor, we can predict a linear increasing of the losses for high output voltage. Our investigations clearly show that the MOSFET losses are greater than they would have to be, especially for high voltages, and our investigations on a large sample of transistors families clearly shows that this law have to be revisited. Indeed simulations show an increase much faster than expected of losses when voltage Vds increases. After compiling data on many power MOSFETs family data sheets a new behavioral model, including the fast evolution of Rdson, for high voltage, has been purposed. This model includes two parameters to be adjusted to a given MOSFET family and which make possible the losses calculation of the concerned family.

Characterization and mechanical properties of epoxy resin reinforced with TiO2 nanoparticles

Epoxy resins with widely different mechanical properties were used as matrices in which functionalized TiO2 particles were randomly dispersed to produce nanocomposites. These nanoparticles, 21 nm in diameter, were dispersed in epoxy resin using ultrasonication or magnetic stirring for 5, 30, and 60 min. The composites with nanometer scale TiO2 particles at 0.5, 1, 5, and 20 wt% were subjected to hardness tests and tensile tests. The results were then compared with the neat epoxy resin. The final mechanical properties of epoxy resin reinforced with TiO2 nanoparticles are hardness 17HV and Young’s modulus for 5% TiO2 (2.813).

A junction characterization for microelectronic devices quality and reliability

Abstract With scaling down of devices for higher performance, ageing effects are becoming more important under standard working conditions. They have an important impact on the reliability of microelectronics devices since changes in the devices operating conditions due to lower power consumption are made. This work considers experimental degradations of the emitter–base characteristics in a transistor; the charge transport phenomena are related to structural properties and the evolution of standard operations, which introduce threshold voltage changes related to high injection effects. Both the junction ideality factor and the transient voltage appear as significant and sensitive parameters for quality and reliability characterization or hardness evaluation. A new reliability parameter RF is introduced and related to ageing of devices and to degradation processes.

Characterization of defect traps in SiO2 thin films influence of temperature on defects

Abstract In order to improve the electrical operation of very thin gate oxide metal-oxide-semiconductor (MOS) devices, it is necessary to understand generated defects in the non-stoichiometric SiO x area and at the Si–SiO 2 interface. For this purpose, we extended our new measurement technique, which is a temperature dependent method, to MOSFETs and Al-gate MOS devices to investigate slow-state traps and their relationship with fast-state traps (influence of technology, temperature and field dependence). With this method, activation energies for slow-state traps can be determined. Hydrogen species have been characterized. These defects are created when the MOS capacity is under a strong electric field that induces injection of electrons by tunnel effect through the silicon dioxide, SiO 2 .

Light emission studies of total dose and hot carrier effects on silicon junctions

The electrical characteristics of silicon light emitting devices are changed in similar ways by X-ray irradiation and hot carrier stresses. Extended hot carrier stress alone causes coalescence of light emission consistent with junction-localized boron passivation by liberated hydrogen. Optical characterization studies demonstrate the formation of junction micro-environments under hot carrier stress.

Characterization of high-density current stressed IGBTs and simulation with an adapted SPICE sub-circuit

Abstract Insulated Gate Bipolar Transistors are devices integrating a MOSFET and a bipolar transistor in a Darlington configuration. These devices have been studied before and after conduction stress. During high temperature operations (200°C) hot carriers can induce degradation in gate oxide, at silicon–oxide interface and into the base–emitter junction. The used IGBT SPICE sub-circuit can describe electrical aging in dynamic and static operation. The knowledge of which parameters are influenced during specific functional stress permits us to compensate for these changes or improve the implementation of the component in a circuit, as well as its use in field conditions.

Characterization of Defect Traps in SiO2 Thin Films

In order to understand the degradation of the electrical operations of metal-oxide-semiconductor (MOS) devices, this work is concerned by the defects generation processes in the non-stoichiometric SiOx, area and at the SiO2 interface. For this purpose, a new measurement technique to study slow-state traps and their relationship with fast-state traps is developed. This method considers capacitance-voltage measurements and temperature effects during the hysteresis cycle.

Insufficiencies of the Single Exponential Model and Efficiency of the Double Exponential Model in the Optimization of Solar Cells Efficiency

Single and double exponential models are confronted to determine the most adapted model for optimization of solar cells efficiency. It is shown that the single exponential model (SEM) presents some insufficiencies for efficiency optimization. The interest of the double exponential model to optimize the efficiency and to achieve an adequate simulation of the operation of solar cells is demonstrated by means of I-V characteristics plotting.