Two sharp and intense emission bands, with maxima of 2.185 and 2.150eV and weak phonon coupling, were investigated in hetero-epitaxial layers. A study of such layers, grown on various substrates with thicknesses of 0.5 to 3.2, showed that the luminescence was produced in interface regions that contained a high density of structural defects. The temperature dependence of these bands revealed an excitonic nature of the recombination. It was proposed that the observed bands originated from the recombination of excitons that were localized at dislocations and associated defects.

A.Naumov, K.Wolf, T.Reisinger, H.Stanzl, W.Gebhardt: Journal of Applied Physics, 1993, 73[5], 2581-3