Benefits of chemical beam epitaxy for micro and optoelectronic applications

This paper reviews the benefits that Chemical Beam Epitaxy (CBE) growth technique can bring to micro and optoelectronic devices. The characteristics of the technique are first underlined for a better understanding of the specific advantages it offers compared to other growth techniques. The first one is the low growth temperature, which pushed the thickness limit in strained InGaAsP multi-quantum well structures. Carbon doping of GaAs and In_0.53Ga_0.47As, and its application to GaAs and InP based npn heterojunction bipolar transistors is another important contribution of CBE which has resulted in successful device development. The last developments in surface cleaning and in situ etching with new amine and chloride sources are presented. The capabilities of CBE for selective and uniform growth on partially masked substrates are illustrated through examples of device planarization and integration. Finally, the most recent improvements in the technology of CBE equipment and their impact on CBE production capabilities are presented.     

Stereochimie en Serie Aziridine—III Etude de l'Isomérie de Rotation d'un Aldéhyde Aziridinique

From the ASIS effect on chemical shifts and from solvent and temperature dependence of the vicinal spin-spin coupling constant of 1-tertiobutyl 2-formyl aziridine, the following conclusion is reached: the less polar rotamer is the s-trans rotamer, which is of lower energy than the s-cis rotamer.     

The CP1 model on the torus: Contribution of instantons

The contribution of instantons to the partition function is calculated for the two-dimensional CP₁ model defined on the torus.     

Electronic and ionic conductivities and point defects in ytterbium sesquioxide at high temperature

From the study of complex impedance diagrams applied to a symmetric cell Pt-Yb₂O₃-Pt, the authors have shown the mixed character of electrical conduction within the ytterbium sesquioxide. The measurements were performed at thermodynamic equilibrium in the temperature range from 1423 to 1623 K and the partial pressure of oxygen range from 10^?12 to 1 atm. The variations of ionic and electronic conductivity as a function of P_O2, were interpreted in terms of point defects e′, ?, V?_Yb and Yb_{$\text{I}\text{?}$}, in the general case of a Frenkel disorder. The relative contributions and the activation energies of conduction of these different defects were determined.     

General Hartree-Fock solutions for a one dimensional δ-function gas

The one dimensional fermion gas with δ-function interactions is studied within the General Hartree-Fock (GHF) framework. Solutions of the eight Fukutome types are constructed by pairing and the corresponding gap equations are solved. The character of the solutions is studied as a function of the particle density.     

Fuzzy Boolean algebras

The purpose of this paper is to generalize the following situation: from the concrete structure $\text{B}$, we define the notion of Boolean algebras; the Stone representation theorem allows us to replace the algebraic study of Boolean algebras by a topological one. Let E be a non-empty set, and J a non-empty ordered set. Note $\text{B}$ the set of all fuzzy subsets of (E,J). We shall introduce the concept of fuzzy Boolean algebra and find a representation theorem. But it will be difficult to speak of the dual fuzzy topological space of a fuzzy Boolean algebra as we shall see further, except in certain particular cases.