Central yielding, as well as peripheral slip, was observed in curved epitaxial silicon slices produced in the laboratory. The central plastic deformation is the result of compressive stresses set up by the entrapment of a hot central region within a colder annular zone. A stress analysis was performed which explains the occurrence and relative intensities of slip in the two regions by reference to the distortion energy densities throughout the slice. A model of the centrally localized plastic deformation in {HI} slices was presented in which the (110) slip vectors inclined to the {HI} surface are activated and produce relief of the central compressive stresses by vertical movements of pyramidal sections of the crystal.[This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 131.94.
An improved acid polishing machine for dislocation-free polishing of copper is reported and its operation described. The main improvements are a compact axial tilt device, provision for rapid interruption of the polishing and inspection of the sample, and a more rigid shaft confinement and alignment. Some useful aids in the chemical polishing techniques are also reported.
Single crystal silicon layers were deposited by the vapor reduction method onto 〈111〉 silicon rods with various concentrations of methane in the deposition gases. Twins appeared only at
CH4
concentrations of 100 ppm and above. In contrast to the results in the case of oxygen addition, twins were found on both
false{true2¯11false}
and
false{1true1¯0false}
faces; and the density of twins on the
false{true2¯11false}
face increased as the 6.7th power of the methane concentration. The general dependence of twin density on the methane concentration suggests that agglomerates of five to seven carbon atoms are responsible for the twin formation. A possible mechanism by which carbon or SiC chains containing less than seven atoms can cause twinning on the
false{true2¯11false}
face is presented.
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