Determining the crystal polarity of compound semiconductors from bend contours

摘要

A method is described which allows the crystal polarity of compound semiconductors with zincblende structure to be unambiguously determined from the contrast of bend contour crossings in TEM dark-field images. The method is derived from a well-established convergent-beam electron diffraction method and exploits effects of the dynamical scattering which are sensitive to the crystal polarity. A simple contrast rule is given which strongly facilitates the polarity analysis in practical experimental work. As examples, applications of the bend contour method to <110> cross-sectional samples of GaAs and of GaSb are presented. Dynamical simulations confirm the contrast behaviour for experimentally useful specimen thickness ranges.