Unified polarity analysis of <110> and <001> Sphalerite-type crystal samples using Bragg-line contrast rules

摘要

The polarity of crystalline materials with sphalerite structure (Ⅲ-Ⅴ compound semiconductors, ZnSe, CdTe, ...) can be derived reliably from the analysis of Bragg-line contrast applying simple contrast rules. The procedure uses polarity-dependent dynamical electron scattering effects near <110> and <001> crystal projections. Using InP as an example, the rules and their applicability are demonstrated for a range of experimentally accessible sample thicknesses, and their validity is confirmed by the comparison of experimental and simulated convergent beam electron diffraction (CBED) patterns. The results show convincingly that the procedure can be applied to crystals with small and large atomic number differences, thus enabling a unified polarity analysis to be carried out.