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.