Characterization of oval defects in molecular beam epitaxy Ga0.7Al0.3As layers by spatially resolved cathodoluminescence

Oval defects in silicon‐doped Ga0.7Al0.3As molecular beam epitaxy grown layers are studied by filtered cathodoluminescence at low temperatures (10 K) in a scanning electron microscope. The spectra obtained inside and outside the defects exhibit very different main emission lines which can be explained by an important variation of the Al/Ga ratio at the center of the defects; this hypothesis is confirmed by localized Auger electron spectroscopy.