The asymptotic spherical aberration and distortion coefficients of electron lenses always depend upon the position of the object, or the magnification, in a very simple way, and furthermore the quantities that specify the distortion are closely related to those giving the spherical aberration. These relationships are set out, and numerical values of the coefficients concerned are tabulated for Glaser's bell-shaped model; both the symmetric and the asymmetric bell are considered, and the effect of scaling with respect to the minimum projector focal length is investigated.

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We carried out mapping of the excess carrier lifetime for a bulk p-type 4H-SiC wafer by the microwave photoconductivity decay (μ-PCD) method, and we compared the lifetime map with structural defect distribution. Several small regions with short lifetimes compared with surrounding parts are found, and they correspond to regions with high-density structural defects. Excess carrier decay curves for this wafer show a slow component, which originates from minority carrier traps. From temperature dependence of the excess carrier decay curve, we found decrease of the time constant of the slow component with increasing temperature. We compared the activation energy of the time constant with that obtained from the numerical simulation, and concluded that the energy level for the minority carrier trap would be 125 meV from the conduction band.

Microstructure of high purity Al foils as high temperature rolled and annealed for electrolytic capacitors was analyzed mainly by transmission electron microscopy. Emphasis was on the dislocation microstructure near the foil surface covered with oxide films and also on the microstructure change along the depth from the surface of the foils. The results were discussed in reference to the etching behavior of the foils. As it goes from the surface to the foil thickness of about 10 m m, dislocation structure changes from relatively random to cellular. The dislocation density and the cellforming tendency increased with cold rolling to 50% reduction. Surface of the foils was examined by AFM to be wavy, with ridges extending parallel to the rolling marks at intervals of 2 to 4 mm. It was also revealed by TEM that band areas with high densities of dislocations and also of oxide particles extended, underneath the oxide layer, along the rolling marks. A larger number of initial-pits were formed by etching along the band areas, suggesting that the areas had acted as preferential nucleation sites for pits. By a prolonged etching, deep tunnel-pits were formed at the sites corresponding to a single dislocation or the aggregates of dislocations. Rolling the foils to 20% reduction prior to etching resulted in increased density and in decreased average size of the pits. This suggests that density of etch pits in the foils could be controlled by controlling the processing conditions before etching.