Regards sur la naissance de la Thermodynamique.

La thermodynamique a eu sa construction dans un environnement scientifique placé sous l’emprise de l’empirisme phénoménologique, contrairement à d’autres disciplines de la physique qui se sont développées dans un cadre de rationalité bien affirmé comme la mécanique newtonienne. Malgré l’importance de la thermodynamique, plusieurs étudiants arrivent à l’université avec des connaissances très limitées et développent des conceptions erronées nous essayons dans ce travail d’amélioration de l’enseignement apprentissage de la thermodynamique pour développer des concepts fondamentaux et Approfondir les concepts de base. Comme elle est structurée, l’enseignement de la thermodynamique devrait nécessairement passer par l’acquisition aussi bien chez que chez le formateur que l’apprenant, de certains outils conceptuels la rendant plus facile à contextualiser et à assimiler. C’est une forme d’exigence en soit, alors qu’à notre avis, ces outils devraient émaner d’une certaine historicité mettant en exergue les conditions et les circonstances dans lesquels ils ont été formalisés. Dans ce récit et en termes de cette historicité, l’auteur a essayé de revenir sur l’apparition des principales grandeurs intervenant dans cette discipline en l’occurrence la chaleur et le travail, dont l’élaboration a pris du temps pour qu’ils soient compris avant de prendre de la consistance. Avec une telle historicité, c’est tout un terrain de communication et d’entente qui est trouvé au carrefour d’une relation enseignant-apprenant basée sur la reconnaissance et la considération mutuelles

Resonant states in GaAs/Ga1-xAlxAs Multi-Quantum-Wells

The effect of buffer layers on resonant states in a Multi-Quantum-Well (MQW) sandwiched between two substrates is investigated here theoretically. These resonances appear as well-defined peaks in the density of states (DOS). The local and total densities of states are obtained from an analytical determination of the Green functions. Due to the substrate/buffer layer/ MQW /substrate interaction, different kinds of resonant states are found and their properties are investigated. We show in particular that an incident electron in the left-hand side substrate is transmitted in the right hand side substrate of the structure with large time delays in the phase time. The peaks in the phase time associated with the transmission coefficient are found to be similar to those corresponding to the DOS. The intensity of these peaks associated with extended states in MQW’s and Tamm like states lying at the MQW/buffer layer interface, strongly depends on the width of the buffer layer.The effect of buffer layers on resonant states in a Multi-Quantum-Well (MQW) sandwiched between two substrates is investigated here theoretically. These resonances appear as well-defined peaks in the density of states (DOS). The local and total densities of states are obtained from an analytical determination of the Green functions. Due to the substrate/buffer layer/ MQW /substrate interaction, different kinds of resonant states are found and their properties are investigated. We show in particular that an incident electron in the left-hand side substrate is transmitted in the right hand side substrate of the structure with large time delays in the phase time. The peaks in the phase time associated with the transmission coefficient are found to be similar to those corresponding to the DOS. The intensity of these peaks associated with extended states in MQW’s and Tamm like states lying at the MQW/buffer layer interface, strongly depends on the width of the buffer layer

Surface and interface shear horizontal acoustic waves in piezoelectric superlattices

7 pages, 7 figures, 1 table.-- PACS: 68.35.Gy; 68.35.Ja; 63.22.+m; 73.20.DxThe propagation of acoustic waves of shear horizontal polarization in infinite and semi-infinite superlattices made of two piezoelectric media is studied within a Green's function method. Localized modes induced by a free surface of the superlattice or a superlattice/substrate interface are investigated theoretically. These modes appear as well-defined peaks of the total density of states inside the minigaps of the superlattice. The spatial localization of the different modes is studied by means of the local density of states. The surface of the superlattice and the superlattice/substrate interface are considered to be either metallized or nonmetallized. We show the possibility of the existence of interface modes, which are without analogue in the case of the interface between two homogeneous media (the so-called Maerfeld–Tournois modes). We also generalize to piezoelectric superlattices a rule about the existence and number of surface states, namely when one considers two semi-infinite superlattices together obtained by the cleavage of an infinite superlattice, one always has as many localized surface modes as minigaps, for any value of the wave vector k (parallel to the interfaces). Specific applications of these results are given for CdS–ZnO superlattices with a free surface or in contact with a BeO substrate.The work of A.B., E.E., D.B., and A.N. has been supported by the Program-in-Aid for Scientific Research (PARS). The work of V.R.V. has been supported by the Dirección General de Enseñanza Superior (Spain) through Grant No. PB96-0916. E.E., A.N. and V.R.V. thank the CNCPRST (Morocco) and CSIC (Spain) for a cooperation project.Peer reviewe

Polaron Effect on the Binding Energy of Shallow Donor in Cylindrical Quantum Dot

In the framework of the effective-mass approximation and the modified Lee-Low-Pines variational method, we present a theoretical study of the effect of the confined longitudinal-optical phonon and two types of surface-optical phonon (top and side mode) on the binding energy of shallow donor in cylindrical quantum dot. The effect of quantum confinement is described by an infinitely deep potential well. The impact of these different phonon modes is important and depends on the dimension of the quantum dot

Vibrational Properties in heterostructures

This is a comprehensive path about theoretical approaches to the vibrational properties in periodic and multilayered structures. The phonons modes taking a large part of our work are detailed beyond the limit offered by the area targeted by this sort of paper. In fact, in many cases of this type of materials, metallic, semiconductor or insulator, these modes are investigated. Although, the electronic properties are devoted, generally, to the semiconductor ones as well as the optical properties will be derived in the second paper of this volume. Another topic can be touched which concerns the coupling effect between phonons and electrons or photons and electrons giving rise to interesting results; but it is not addressed here. Throughout this paper, we bring forth the theoretical model currently used by us, and the results obtained in consequence. This model is called the response function based on the Green function and its properties are stressed as well as the results obtained.This is a comprehensive path about theoretical approaches to the vibrational properties in periodic and multilayered structures. The phonons modes taking a large part of our work are detailed beyond the limit offered by the area targeted by this sort of paper. In fact, in many cases of this type of materials, metallic, semiconductor or insulator, these modes are investigated. Although, the electronic properties are devoted, generally, to the semiconductor ones as well as the optical properties will be derived in the second paper of this volume. Another topic can be touched which concerns the coupling effect between phonons and electrons or photons and electrons giving rise to interesting results; but it is not addressed here. Throughout this paper, we bring forth the theoretical model currently used by us, and the results obtained in consequence. This model is called the response function based on the Green function and its properties are stressed as well as the results obtained

Electronic properties in heterostructures

Using the interface response, the effect of internal surface of Single Quantum Well (SQW) and of Superlattice (SL) (Substrate / Single Quantum Well and of Substrate / Superlattice interfaces) are studied in term of changing the heterostructures parameters and keeping constant the parameters of substrate. Surface and interface considered as well as planar defects are associated with the states which are localised in mini gaps (MG). Electronic properties are touched in this way and their investigation is made by band structures and variational density of states (DOS).Using the interface response, the effect of internal surface of Single Quantum Well (SQW) and of Superlattice (SL) (Substrate / Single Quantum Well and of Substrate / Superlattice interfaces) are studied in term of changing the heterostructures parameters and keeping constant the parameters of substrate. Surface and interface considered as well as planar defects are associated with the states which are localised in mini gaps (MG). Electronic properties are touched in this way and their investigation is made by band structures and variational density of states (DOS)