Engineering topics
Publications and source records attributed to Heinemann, K..
Description of a new method which makes it possible to reduce drastically the resolution-limiting influence of chromatic aberration, and thus to obtain high-quality images, by selecting the image-forming electrons that have passed through a small annular zone of an objective lens. In addition, the manufacture of special objective-lens aperture diaphragms that are needed for this method is also described.
Hollow-cone illumination techniques, using an annular objective aperture located behind back focal plane of objective lens, increase image contrast and minimize chromatic aberrations.
Particular features and the performance of two experimental systems are described for quantitative studies of thin-film nucleation and growth processes including epitaxial depositions. System I consists of a modified LEED-Auger instrument combined with high-resolution electron microscopy. System II is a UHV electron microscope adapted for in-situ deposition studies. The two systems complement each other ideally, and the combined use of both can result in a comprehensive investigation of vapor deposition processes not obtainable with any other known method.
Electron micrographs have been obtained which clearly show the existence of a void network in amorphous Ge films formed at substrate temperatures of 25 and 150 C, and the absence of a void network in films formed at higher substrate temperatures of 200 and 250 C. These results correlate quite well with density measurements and predictions of void densities by indirect methods.
Epitaxial deposition of Au on ultrahigh vacuum cleaved mica during early nucleation and growth
Bragg-reflex images of small individual crystallites in the size range of 20-100 A diameter with known crystallographic orientation were used in a transmission electron microscope to determine in-situ: (a) the relationship between objective lens current (or accelerating voltage) changes in discrete steps and corresponding defocus, (b) the spherical aberration coefficient, and (c) the axial chromatic aberration coefficient of the objective lens. The accuracy of the described method is better than 5%. The same specimen can advantageously be used to properly aline the illuminating beam with respect to the optical axis.
Lattice planes and interplanar spacings of small vapor deposited gold crystals, using transmission electron microscopy