Search results for "Lattice plane"

On the lattice of J-subnormal subgroups

1992

Modulational instability and two-dimensional dynamical structures

2008

A process of nonlinear structure formation on a two-dimensional lattice is proposed. The basic model consists of a two-dimensional lattice equipped at each node with a molecule or dipole rotating in the lattice plane. The interactions involved in the model are reduced to a periodic lattice. Such a discrete system can be applied to the problem of molecule adsorption on a substrate crystal surface, for instance. The continuum approximation of the model leads to a 2-D sine-Gordon system including nonlinear couplings, which itself can be reduced to a 2-D nonlinear Schrodinger equation in the low amplitude limit. Spatio-temporal structure formation is investigated by means of numerical simulatio…

Strain state analysis of InGaN/GaN - sources of error and optimized imaging conditions.

2006

Transmission electron microscopy investigation of the chemical composition of In x Ga 1-x N/GaN layers by strain state analysis can lead to substantial artefacts. We evaluated simulated images in dependence of specimen thickness, specimen orientation and objective lens defocus. We observed that the measurement is in agreement with the true strain profile for certain conditions only. An analysis of error sources revealed that artefacts are mainly caused by a combination of delocalization and the composition dependence of the phases of the beams contributing to the image formation. The delocalization effect is minimized for interference of the undiffracted beam with one of the 000 ± 2 beams. …