THE CONSEQUENCES OF THE ATOMIC SIZE EFFECT IN QUANTITATIVE HIGH-RESOLUTION ELECTRON-MICROSCOPY

We investigate the effect upon HREM images of the static atomic displa cements (SD) present in crystalline alloys with atomic size effect. Ou r method is to compare pairs of images of the same distributions of at oms (in III-V alloys) calculated with and without taking the SD into a ccount. We show that large differences usually exist between these ima ges, assess them quantitatively, and demonstrate that proper considera tion of the SD is essential to achieve reliable composition analysis b y HREM, in particular when the 'chemical mapping' technique is used. T he effect of the SD depends on the specimen thickness and on the objec tive lens defocus.