InGaAs/GaAs/alkanethiolate radial superlattices: Experimental

A radial InGaAs/GaAs/1-hexadecanethiol superlattice is fabricated by the roll-up of a strained InGaAs/GaAs bilayer passivated with a molecular self-assembled monolayer. Our technique allows the formation of multi-period inorganic/organic hybrid heterostructures. This paper contains the detailed experimental description of how to fabricate these structures.Comment: 2 pages, no figures, Version 2; minor changes (fixed typos and update references

Die direkte Messung von Stapelfehlerenergien

Different methods for determining stacking fault energies from dislocation configurations observed in the electron microscope are discussed. Configurations discussed are simple, threefold, and fourfold ribbons, arrays of many parallel ribbons, and dislocation nodes. The latter are treated taking the mutual interaction of the partials approximately into account. Results are given for measurementsin graphite, MoS$_{2}$, AIN, and talc

The buckling of a thin plate due to the presence of an edge dislocation

lt is shown that an edge dislocation parallel to the surface of a thin foil causes buckling of this foil by an angle of about $\theta$ = b/t. (b = Burgers vector; t = thickness of the foil). The angle $\theta$ depends on the position of the dislocation. lt is maximum for a dislocation in the middle of the foil and it tends to zero as the dislocation approaches to the surface. lt is shown that the buckling is responsible for the discontinuous change in contrast along a dislocation as observed in transmission electron microscopy. The sense of buckling which can be determined by means of Kikuchi lines depends on the sign of the dislocation. The effect therefore provides an easy means to determine the sign of edge dislocations

Surface effects associated with dislocations in layer crystals

Dislocation configurations in thin foils cannot be accurately interpreted unless the effects of anisotropy and surfaces on the stresses and energies of edge and screw dislocations are known. Expressions for these effects are derived here for a semi-infinite hexagonal crystal with dislocations in the basal plane. lt is then shown that in plate-like crystals, as used in electron-microscopic investigations, the finite thickness of the specimen leads to observable effects on the dislocation patterns. In particular, the width of a ribbon decreases as it approaches the surface, due to the reduced repulsion between the partials, so that care is needed in deducing stacking fault energies from ribbon widths. Also the energy of a dislocation is a function of its distance from a surface, so that if it is crossed by a surface step it suffers a "refraction" which, in simple cases, follows Snell's law. lt is further shown that dislocations will tend tobe aligned with surface steps, artd the interaction energy between a step and a parallel dislocation line can thus be derived from experimental data. Finally, a method is suggested for obtaining information on the elastic constants from electron microscopic data