Structure and intermixing of GaSb∕GaAs quantum dots

We present cross-sectional scanning tunneling microscopy results of GaSb quantum dots in GaAs, grown by metalorganic chemical vapor deposition. The size of the optically active quantum dots with base lengths of 4–8 nm and heights of about 2 nm is considerably smaller than previously published data obtained by other characterization methods. The local stoichiometry, obtained from atomically resolved images, shows a strong intermixing in the partly discontinuous wetting layer with an average GaSb content below 50%, while the GaSb content of the partly intermixed quantum dots is between 60% and 100%.