Cathodoluminescence characterization of InGaSb crystals

The nature and the spatial distribution of radiative defects in In_xGa_1-xSb grown by the vertical Bridgman method have been studied by cathodoluminescence (CL) in a scanning electron microscope. The CL results have been complemented by X-ray microanalysis and backscattered electron imaging to relate the local luminescence properties to the chemical composition. Measurements of the band gap energy from the CL spectra, supported by X-ray compositional mappings, reveal an effective incorporation of In in the matrix, leading to the formation of the ternary alloy in the whole volume of the ingot. A band often observed in the CL spectra, peaked at about 20 meV below the band gap energy, is attributed to the presence in the ternary alloy of an acceptor level that would correspond to the V_Ga-Ga_Sb acceptor in GaSb.