ABSTRACT
GaxIn1-xASyP1-y layers of different substrate orientations grown by MOVPE with a composition located inside the predicted miscibility gap were compared. The investigations were carried out by STEM using bright-field and atomic number (Z-) contrast imaging, PEELS and CBED. For the case of a substrate misorientation of 2° (towards {111} B) the layers show strong contrast variations in bright-field and Z-contrast images. In this case we determined the local chemical composition of the decomposed phases by PEELS to Δx=0.02 and Δy=0.04, using a 0.5 nm probe. These results were confirmed by CBED measurements. In the case of an exactly orientated substrate we found only weak hints for chemical fluctuations.
