Influence of doping level on the cathodoluminescence of Se-doped GaSb crystals

The influence of the doping level on the radiative recombination properties of GaSb:Se crystals has been investigated by cathodoluminescence (CL) microscopy and spectroscopy in the scanning electron microscope. CL images evidence a high dislocation density and dopant segregation around the dislocation cores in highly-doped crystals. A progressive reduction of the Se content leads to a lower dislocation density and a more uniform luminescence spatial distribution. CL spectra reveal the existence of three Se-related emission bands, centred in all the samples investigated at about 765, 740 and 719 meV, whose relative intensity is influenced by the doping level. Measurements carried out at different temperatures and excitation densities indicate that these bands can be attributed to transitions from the conduction band to deep acceptor levels