FUZZY-LOGIC APPROACHES TO THE ANALYSIS OF HREM IMAGES OF III-V COMPOUNDS

It is known that high-resolution electron microscopy (HREM) can provid e quantitative information on the properties of crystalline materials. The HREM patterns of layered structures of III-V semiconductors vary with the chemical composition of the latter within the sublattices, wh ich is also influenced by interdiffusion, Local variations of the crys tal cell similarity are recorded for image analysis and compared with templates of known material composition, Of the advanced theories of d ata interpretation, the now well-established fuzzy logic is highly sui ted for corresponding image processing techniques, Combining neighbour ing image cell similarities, the underlying chemical composition is ev aluated by applying fuzzy logic criteria of inference to masks of abou t 1 nm x 1 nm in size. The new approach can be used to localize region s of significant changes in composition, i.e. edge detection, and to d etermine the composition across the interface region, The methods intr oduced prove successfully applicable to simulated as well as to experi mental images of AlAs/AlxGa1-xAs. Similarity/composition relations of nonlinear as well as nonmonotonic characteristics are studied to estab lish an alternative fuzzy logic approach.