Generation-Recombination noise analysis in ungated HEMT structure to determinate the activation energy and capture cross-section of traps

Low frequency noise of ungated GaAs/AlGaAs two-dimensional electron gas (2 DEG) heterostructure grown by molecular beam epitaxy (MBE) was investigated over a wide range of temperatures from 4 K to 300 K. In the frequency range from 1 Hz to 100 KHz, noise power spectral densities (PSD) can be described as superposition of flicker noise, thermal noise and several generation-recombination (G-R) noise components. The temperature dependence of the (G-R) noise arising from the traps was used to deduce the thermal activation energies and cross sections. The present results are compared to those of the literature to identify the physico-chemical nature of traps responsible of the G-R noise.Low frequency noise of ungated GaAs/AlGaAs two-dimensional electron gas (2 DEG) heterostructure grown by molecular beam epitaxy (MBE) was investigated over a wide range of temperatures from 4 K to 300 K. In the frequency range from 1 Hz to 100 KHz, noise power spectral densities (PSD) can be described as superposition of flicker noise, thermal noise and several generation-recombination (G-R) noise components. The temperature dependence of the (G-R) noise arising from the traps was used to deduce the thermal activation energies and cross sections. The present results are compared to those of the literature to identify the physico-chemical nature of traps responsible of the G-R noise

Modeling of photonic band gap in two dimensional photonic crystals made by sol gel process

Photonic band gap of two dimensional photonic crystals fabricated by SiO2/ZrO2 or SiO2/TiO2 with sol-gel process in which the refractive index varied in the range of 1.51 to 1.57 has been investigated in the present paper. The structure studied consists of circular air holes of radius r embedded in matrix, while a is the constant of triangular lattice. Finite difference time domain method (FDTD) with perfectly matched layers (PML) was used to calculate the transmission spectrum by FullWAVE software. The results of simulation clearly demonstrate the existence of photonic band gap of which the position and the width are strongly affected by refractive index. In the other hand, the effects of geometric parameters (air hole radius r and lattice period a) on the photonic band gap have been investigated in this work

Theoretical study of a nonlinear fast silicon photoconductive switch

Silicon-On-Insulator waveguide can be used as photoconductor, the light being coupled in the silicon film by a diffraction grating. Nonlinear effects are induced by the photogeneration of electron-hole pairs. This leads to photocurrent variations which are much faster than in linear regime and also much steeper than the incident light pulse. A model is presented which takes into account the refractive index variations arising from both the excess carrier density and the temperature rise induced by carrier recombination and Joule effect. The photocurrent is calculated for various values of the incident light power, incidence angle and pulse duration

Characterization of interface traps on MOS transistor submicronic by the three level charge pumping

Because of its efficiency, its high precision and its easy use regarding to classical techniques of Si-Sio2 (C-V, DLTS, Conductance$\ldots$), interface characterization, the charge pumping technique has seen a large evolution these years. Many improvements have been made other, derivation techniques have been developed (at three-level charge pumping, spectroscopic charge pumping $\ldots$) This technique is particularly used for very slight geometry MOS transistors damaging, where other techniques have no utility. This damaging often leads to the creation of a fixed trapped charge in the oxide coat and active electronically defaults in the oxide Semi-conductor interface after the application of ageing constraint (ionizing radiation, injection carrier). This ageing is so pronounced when the dimensions are slight this represents the main obstacle that the microelectronics must face. In this article we simulate the three-level charge pumping technique with SPICE3F4 simulator. This simulation will permit the obtaining of spatial and energetic spread of defaults at the interface

Phase matched magnetooptical single mode rib waveguides based on geometrical adjustments

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MODELISATION NUMERIQUE PAR LA METHODE DES ELEMENTS FINIS D’UN PHOTOCONDUCTEUR A CAVITE SUBMICRONIQUE

Ce travail présente l’étude du fonctionnement dynamique des dispositifs pour la commutation optique dans ledomaine des impulsions de quelque nanosecondes. Ces dispositifs sont constitués d’un guide d’onde non linéaireen silicium sur saphir, avec coupleur à réseau de diffraction.Le principe de fonctionnement de ce dispositif repose sur une création importante des porteurs par absorption del’onde guidée, il doit recevoir donc le maximum de lumière, pour cela le couplage par réseau doit être efficace.Pour cela nous avons modélisé le comportement de ce dispositif en régime dynamique (en tout optique), par laméthode des éléments finis, en tenant compte de la variation de l’indice de réfraction avec la densité des porteursen excès, et de l’effet de l’élévation de la température résultant de recombinaisons des porteurs.Nous avons ainsi expliqué l’existence de deux commutations (l’une d’origine électronique et l’autre d’originethermique) sur les intensités absorbées ou transmises.    This work presents the study of the dynamic working of devices for the optic commutation in the domain ofimpulses of some nanoseconds. These devices are constituted of a wave guide no linear in silicon on sapphire,with coupler to system of diffraction.The principle of workings of this device reclines on a creation important of carriers by absorption of the waveguided, it must receive the maximum of light therefore, for it the coupling by system must be efficient.We are presented the model of this device in dynamic regime (in all optic), by the finite element method, whileholding amount of the variation of the refraction indication with the density of carriers in excess, and the effectof the elevation of the temperature results recombination of carriers.We have explains the existence of two commutations thus (one of electronic origin and the thermal origin other)on the absorbed intensities either transmitted

Evidence for acceptor surface states in GaAs planar-type devices

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Modeling and analysis of birefringence in magneto-optical thin film made by SiO2/ZrO2 doped with ferrite of cobalt

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Birefringence in magneto-optical rib waveguides made by SiO2/TiO2 doped with g-Fe2O3

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