Characterization of GaSb-based heterostructures by scanning electron microscope cathodoluminescence and scanning tunnelling microscope

The luminescence of GaSb and AlGaSb layers grown on GaAs substrates by metal organic vapour phase epitaxy has been studied by means of cathodoluminescence (CL) using a scanning electron microscope. CL plane-view analysis reveals a distribution of defects, as misfit dislocations, in some of the structures. The luminescence bands observed in the GaSb layers are related to near band edge recombination and to an excess of Ga. In the case of AlGaSb/GaSb heterostructure emission bands related to the ternary compound and to donor-acceptor recombination are detected. In addition, with the aid of a scanning tunnelling microscope (STM), local electronic properties, such as conductance and surface energy gap, were studied in sample cross-sections. The results obtained from imaging and spectroscopy modes of STM enabled us to image the single AlGaSb layer.