DIRECT OBSERVATION OF DISLOCATION CORE STRUCTURES IN CDTE GAAS(001)/

A strategy is presented for determining sublattice polarity at defects in compound semiconductors. Core structures of 60-degree and Lomer di slocations in the CdTe/GaAs(001) system have been obtained by the appl ication of maximum-entropy analysis to Z-contrast images (Z is atomic number) obtained in a 300-kilovolt scanning transmission electron micr oscope. Sixty-degree dislocations were observed to be of the glide typ e, whereas in the case of Lomer dislocations, both a symmetric (Hornst ra-like) core and an unexpected asymmetric structure made up of a four fold ring were seen.