Imaging of three-dimensional (Si,Ge) nanostructures by off-axis electron holography.

Quantitative phase mapping in transmission electron microscopy is applied to image the three-dimensional (3D) morphology of (Si,Ge) islands grown on Si substrates. The phase shift of the transmitted electrons induced by the crystal inner potential was recorded by using off-axis electron holography. The analysis of the experimental data requires the knowledge of the mean inner potential (MIP) of the (Si,Ge) solid solution.

The transition between conformal atomic layer epitaxy and nanowire growth.

Conformal atomic layer deposition of thin Sb(2)S(3) layers takes place epitaxially on suitable substrates at 90 degrees C. More elevated deposition temperatures increase the mobility of the solid and result in the diffusion of Sb(2)S(3) along surface energy gradients. On an Sb(2)Se(3) wire that presents the high-energy c facet at its extremity, this results in the axial elongation of the wire with a Sb(2)S(3) segment.

Relativistic effects in elastic scattering of electrons in TEM.

Transmission electron microscopy typically works with highly accelerated thus relativistic electrons. Consequently the scattering process is described within a relativistic formalism. In the following, we will examine three different relativistic formalisms for elastic electron scattering: Dirac, Klein-Gordon and approximated Klein-Gordon, the standard approach.

Electron microscope characterization of CdSe/ZnSe quantum dots based on molecular dynamics structure relaxations.

Molecular dynamics simulations using empirical potentials are applied to characterize the structure, the energy relaxation and the stability of pyramidal-shaped quantum dots in the CdSe/ZnSe system. The relaxed structure models are used for a reliable interpretation of electron microscope investigations to analyze the size, the shape and the strain fields of the quantum dots. Though the elastic strains modify the electron microsope image contrast by creating virtual truncations of the pyramids or additional black-white lobes, optimum imaging conditions chosen will reveal the shape and the size of the dots.

TEM characterization of self-organized CdSe/ZnSe quantum dots.

CdSe quantum dots (QDs) grown on ZnSe were investigated by various transmission electron microscopy (TEM) techniques including diffraction contrast imaging, high-resolution and analytical transmission electron microscopy both of plan-view as well as cross-section specimens. The size of the QDs ranges from about 5-50 nm, where from the contrast features in plan-view imaging two classes can be differentiated. In the features of the smaller dots there is no inner fine structure resolvable.