MAPPING THE COMPOSITION OF MATERIALS AT THE ATOMIC-LEVEL

The composition of materials can now be quantitatively mapped with near-atomic resolution and sensitivity. The procedure combines chemical lattice imaging (which sensitively records the compositional information) with vector pattern recognition (which efficiently extracts and quantifies the local information content). In this way, single and double atom substitutions in individual atomic columns of semiconductors can be detected with about 60% and 90% confidence, respectively. Here we describe the theoretical underpinnings of quantitative chemical mapping, and briefly present examples of its application to the study of solid state processes at the atomic level.