Transmission electron microscopy has been used to observe Al segregation ar
ound the threading dislocations in Al0.1Ga0.9N and Al0.3Ga0.7N grown by met
alorganic chemical vapor deposition on 6H-SiC. Dislocation lines were found
to have up to 70% more Al concentration than those regions free of disloca
tions in the matrix. The Al-depleted regions around the dislocations are sh
own to be within a few nanometers from the dislocation lines. The results a
lso show that more Al segregate to edge dislocations than to screw ones. (C
) 2001 American Institute of Physics.