Atom Probe Tomography Analysis of InAlGaAs Capped InAs/GaAs Stacked Quantum Dots with Variable Barrier Layer Thickness

International audienc

3D compositional analysis at atomic scale of InAlGaAs capped InAs/GaAs QDs

International audienceThe 3D compositional distribution at the atomic-scale of InAs/GaAs quantum dots (QDs) with an InAlGaAs capping layer has been obtained by atom probe tomography. A heterogeneous distribution of Al atoms has been revealed. An Al-rich ring around the QDs has been observed. A detailed analysis of the QDs composition evidences a high degree of In/Ga intermixing, with an increasing In gradient in the growth direction. The atomic scale analyses of these nanostructures are essential to understand their functional properties

Model reduction - an algebraic, geometric and operator theoretic approach Final scientific report

Available from TIB Hannover: F98B1713 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEGerman-Israeli Foundation for Scientific Research and Development (GIF), Oberschleissheim (Germany)DEGerman

Some analytical properties of #gamma#-convex functions on the real line

This paper deals with analytical properties of #gamma#-convex functions on the real line, which are defined as those f satisfying the inequality f(x'_1)+f(x'_2)#<=#f(x_1)+f(x_2) for x'_i element of [x_1, x_2], parallel x_i-x'_i parallel =#gamma#, i=1,2, whenever parallel x_1-x_2 parallel >#gamma# for some given positive #gamma#. This class contains all convex functions and all periodic functions with period #gamma#. In general, #gamma#-convex functions do not have such good properties as convex functions. For instance, there exist #gamma#-convex functions which are nowhere continuous or totally unbounded. But #gamma#-convex functions possess so-called conservation properties, i.e., properties which remain true on every bounded interval, or even on the entire domain, if only they hold true on an arbitrary closed interval with length #gamma#. It is shown that boundedness, bounded variation, integrability, continuity and differentiability almost everywhere are some conservation properties of #gamma#-convex functions on the real line. Further on, #gamma#-convex functions also have infection properties, i.e., properties which certainly infect to other places, once appear somewhere, for example, discontinuity. Besides, some equivalent characterizations of #gamma#-convexity are given. Additionally, some ways for generating and representing #gamma#-convex functions are described. (orig.)Available from TIB Hannover: RR 1606(95-14) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman