Impurity complex formation around extended defects was investigated by using high-resolution scanning photoluminescence methods at 100K. Good spectral resolution permitted the detailed identification of various recombination processes (Z-bands at 1.30 and 1.36eV, self-activated bands, band-edge luminescence) and high spatial resolution (less than 5) in the case of extended defects. The broad maxima of the Z-band photoluminescence profiles were correlated with dislocation etch pits, but the width of the profile proved that the Z-recombination mechanism could not be related to the dislocation core itself but to an impurity cloud near to the dislocation. When the local concentration of the Z-impurity was further increased, a dip appeared in the shape of the maxima of the photoluminescence profiles. It was noted that the positions of these dips coincided with the maxima of the self-activation band at 1.45eV. Impurity complex formation was used to explain the profiles.

A.Gukasyan, A.Kvit, Y.Klevkov, S.Oktyabrsky: Solid State Communications, 1996, 97[10], 897-902