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We present an abstract mathematical and numerical analysis for Drift‐Diffusion equation of heterojunction semiconductor devices with Fermi‐Dirac statistic. For the approximation, a mixed finite element method is considered. This can be profitably used in the investigation of the current through the device structure. A peculiar feature of this mixed formulation is that the electric displacement D and the current densities jn and jp for electrons and holes, are taken as unknowns, together with the potential φ and quas‐Fermi levels φn and φp. This enably D, jn and jp to be determined directly and accurately. For decoupled system, existence, uniqueness, regularity and stability results of the approximate solution are given. A priori and a posteriori error estimates are also presented. A nonlinear implicit scheme with local time steps is used. This algorithm appears to be efficient and gives satisfactory results. Numerical results for an heterojunction bipolar transistor, In two dimension, are presented.

We present a semi‐quantum model including tunneling effects across an abrupt heterojunction. The discontinuity of the effective masses and the energy bands are considered. The quantum transmission conditions for the quasi‐Fermi levels are obtained using WKB approximation. We use mixed finite element approach and a two dimensional mesh which is double‐valued for quasi‐Fermi levels at a heterojunction. A GaAs/GaAIAs heterojunction diode is then simulated using both drift‐diffusion and semi‐quantum model by varying doping density at low temperature.

The purpose of this paper is to provide a new three dimension physically based model to calculate the initial stress in silicon germanium (SiGe) film due to thermal mismatch after deposition. We should note that there are many other sources of initial stress in SiGe films or in the substrate. Here, the author is focussing only on how to model the initial stress arising from thermal mismatch in SiGe film. The author uses this initial stress to calculate numerically the resulting extrinsic stress distribution in a nanoscale PMOS transistor. This extrinsic stress is used by industrials and manufacturers as Intel or IBM to boost the performances of the nanoscale PMOS and NMOS transistors. It is now admitted that compressive stress enhances the mobility of holes and tensile stress enhances the mobility of electrons in the channel.

During thermal processing, thin film materials like polysilicon, silicon nitride, silicon dioxide, or SiGe expand or contract at different rates compared to the silicon substrate according to their thermal expansion coefficients. The author defines the thermal expansion coefficient as the rate of change of strain with respect to temperature.

Several numerical experiments have been used for different temperatures ranging from 30 to 1,000°C. These experiments did show that the temperature affects strongly the extrinsic stress in the channel of a 45 nm PMOS transistor. On the other hand, the author has compared the extrinsic stress due to lattice mismatch with the extrinsic stress due to thermal mismatch. The author found that these two types of stress have the same order (see the numerical results on Figures 4 and 12). And, these are great findings for semiconductor industry.

Front-end process induced extrinsic stress is used by manufacturers of nanoscale transistors as the new scaling vector for the 90 nm node technology and below. The extrinsic stress has the advantage of improving the performances of PMOSFETs and NMOSFETs transistors by enhancing mobility. This mobility enhancement fundamentally results from alteration of electronic band structure of silicon due to extrinsic stress. Then, the results are of great importance to manufacturers and industrials. The evidence is that these results show that the extrinsic stress in the channel depends also on the thermal mismatch between materials and not only on the material mismatch.

The model the author is proposing to calculate the initial stress due to thermal mismatch is novel and original. The author validated the values of the initial stress with those obtained by experiments in Al-Bayati et al. (2005). Using the uniaxial stress generation technique of Intel (see Figure 2). Al-Bayati et al. (2005) found experimentally that for 17 percent germanium concentration, a compressive initial stress of 1.4 GPa is generated inside the SiGe layer.

The purpose of this paper is to develop and apply accurate and original models to understand and analyze the effects of the fabrication temperatures on thermal-induced stress and speed performance of nano positively doped metal oxide semiconductor (pMOS) transistors.

The speed performances of nano pMOS transistors depend strongly on the mobility of holes, which itself depends on the thermal-induced extrinsic stress σ. The author uses a finite volume method to solve the proposed system of partial differential equations needed to calculate the thermal-induced stress σ accurately.

The thermal extrinsic stress σ depends strongly on the thermal intrinsic stress σ₀, thermal intrinsic strain ε₀, elastic constants C11 and C12 and the fabrication temperatures. In literature, the effects of fabrication temperatures on C11 and C12 needed to calculate thermal-induced stress σ₀ have been ignored. The new finding is that if the effects of fabrication temperatures on C11 and C12 are ignored, then, the values of stress σ₀ and σ will be overestimated and, then, not accurate. Another important finding is that the speed performance of nano pMOS transistors will increase if the fabrication temperature of silicon-germanium films used as stressors is increased.

To predict correctly the thermal-induced stress and speed performance of nano pMOS transistors, the effects of fabrication temperatures on the elastic constants required to calculate the thermal-induced intrinsic stress σ₀ should be taken into account.

There are three levels of originalities. The author considers the effects of the fabrication temperatures on extrinsic stress σ, intrinsic stress σ₀ and elastic constants C11 and C12.

Shows how a strongly non‐linear semiconductor equation can be solved via homotopy deformation methods combined with the arclength continuation procedures. The fundamental goal of these methods is to overcome the instabilities or the failure of the classical Newton‐Raphson’s schemes which appear when the non‐linearity is strong or near limit or bifurcation points. The system, in its artificial transient form, is discretized by the non‐linear implicit scheme with local time steps. Uses the mixed finite element (MFE) approach. Presents numerical results, in two dimension, for a realistic device: an Abrupt Heterojunction Bipolar Transistor working as an amplifier.

A stationary 3D energy‐transport model valid for semiconductor heterostructure devices is derived from a semiclassical Boltznmann equation by the moment method. In addition to the well‐known conservation equations, we obtain original interface conditions, which are essential to have a mathematically well‐posed problem. An appropriate modelling of the physical parameters appearing in the system of equations is proposed for gallium arsenide. The model being written and its particularities mentioned, we present a novel numerical algorithm to solve it. The discretization of the equations is achieved by means of standard and mixed finite element methods. We apply the model and numerical algorithm to simulate a 2D AlGaAs/GaAs MODFET. Comparisons between expenrimental measurements and calculations are carried out. The influence of the modelling of the physical parameters, especially the electron mobility and the energy relaxation time, is noted. The results show the satisfactory behaviour of our model and numerical algorithm when applied to GaAs heterostructure devices.

Some results related to the algorithmic behaviour in semiconductor devices numerical simulations (‐static case‐), using mixed finite elements and operator splitting techniques have been presented in. The drift‐diffusion model written with the electrostatic potential φ and the quasi‐Fermi levels φn and φp is used.

In this paper, we present the results of submicron pseudomorphic AlGaAs/InGaAs/ GaAs HEMT simulations. Our main interest is the study of electronic temperature behavior in the device and improvement of the current‐voltage characteristic curves. Three types of models are being used. The first is the well known drift‐diffusion model. The second is of the hydrodynamic type and the third is a combination of the two preceding models. The numerical treatment is based on the discretization by the Galerkin finite element method for both Poisson and continuity equations with the streamline‐diffusion method being used for the energy equation. A comparison of the different approaches have been realized and a synthesis on the validity of each of these models is being drawn.

This paper aims to examine the mediating role of brand satisfaction and brand trust in brand equity antecedents and outcomes through an empirical investigation of brand equity elements.

A survey was conducted in Pune and Mumbai, two prominent cities of India. A structured questionnaire focussed on garnering responses on measuring brand equity antecedents and outcomes was circulated to the cell phone users. The questionnaire aimed to assess the role of two additional variables, namely, brand satisfaction and brand trust, in the existing and the conceptual model of brand equity (Keller, 2001). Based on the data analysis, a structural equations path and the mediating model were developed.

The findings of this study show that the new brand equity model is highly relevant in predicting brand equity as compared to the existing brand equity model (Keller, 2001). The brand equity mediation model clearly elucidates the role of brand trust and brand satisfaction.

With reference to a theoretical contribution, the study broadens the existing hypothetical model of brand equity. The findings of this research provide a strategic and analytical model for brand managers to build brand relationships among their consumers.

The present study challenges the existing model of brand equity (Keller, 2001) and further makes an effort to fill in the gaps in the existing theoretical model of brand equity.

Este documento tiene como objetivo examinar el papel mediador de la satisfacción con la marca y la confianza con la marca en los antecedentes y resultados de la equidad de marca a través de una investigación empírica de los elementos de equidad de marca.

Se realizó una encuesta en Pune y Mumbai, dos ciudades prominentes de la India. Se distribuyó a los usuarios de teléfonos móviles un cuestionario estructurado centrado en obtener respuestas para medir los antecedentes y resultados del valor de marca. El objetivo del cuestionario era recoger información para evaluar el papel de dos variables adicionales, la satisfacción con la marca y la confianza en la marca en el modelo existente y conceptual del valor de marca (Keller, 2001). El análisis de datos se llevó a cabo a través de la metodología de ecuaciones estructurales y modelo de mediación.

Los hallazgos de este estudio muestran que el nuevo modelo de equidad de marca es muy relevante para predecir el valor de marca en comparación con el modelo de marca existente (Keller, 2001). El modelo de mediación de la equidad de marca aclara el rol de la confianza y la satisfacción con la marca.

En relación a la contribución teórica, el estudio amplía el modelo existente de valor de marca. Los resultados de esta investigación proporcionan un modelo estratégico y analítico para que los gerentes creen relaciones de marca entre sus consumidores.

El presente estudio desafía el modelo existente de equidad de marca (Keller, 2001) y además hace un esfuerzo por llenar los vacíos en el modelo teórico existente de equidad de marca.

Equidad de marca, Satisfacción con la marca, Confianza en la marca, Análisis de ecuaciones estructurales, Análisis de mediación

Artículo de investigación

The paper aims to evaluate drying performance of earth mortar by solar drying for more durability, minimize pathologies in traditional construction and determine the influence of temperature and humidity on the microstructure of earth mortar using static gravimetric method.

A convective solar dryer was used for the pretreatment of building and solid materials for construction.

The humidity influences the mortar sorption – surface water sorption of earth mortar increased with increasing temperature.

The study used a novel method for pretreatment building materials by using solar dryer.