Spherical-aberration correction in tandem with the restoration of the exit-plane wavefunction: synergetic tools for the imaging of lattice imperfections in crystalline solids at atomic resolution

Abstract

With the availability of resolution-boosting and delocalization-minimizing techniques, aberration-corrected high-resolution transmission electron microscopy is currently enjoying great popularity with respect to the atomic scale imaging of lattice imperfections in crystalline solid-state materials. In the present review, the most striking practical benefits arising from the synergetic combination of two sophisticated state-of-the-art techniques, i.e. spherical-aberration-corrected imaging as well as the numerical restoration of the exit-plane wavefunction from a focal series of high-resolution micrographs, are illustrated by highlighting their combined use for the atomic-scale characterization of misfit dislocations, stacking faults and grain boundaries in common semiconductor materials and metastable metal phases. For these purposes recent progress is reviewed in the atomic-scale characterization of (i) Lomer-type misfit dislocations at In_xGa_1-xAs/GaAs heterointerfaces and extrinsic stacking fault ribbons in GaAs together with the associated lattice displacements [Tillmann et al. (2004) Microsc Microanal 10:185], (ii) the core structure of chromium implantation-induced Frank partial dislocations in GaN [Tillmann et al. (2005) Microsc Microanal 11:534] as well as (iii) tilt boundaries between β-phase Ta crystallites in thin metallization layers [Tillmann et al. (2006) Phil Mag, in press]. In addition, practical advantages are demonstrated of the retrieval of the exit-plane wavefunction not only for the measurement and subsequent elimination of residual lens aberrations still present in aberration-corrected microscopy, but also for the proper alignment of specimens during operation of the electron microscope.