The design of cost-effective standards for the quality of nano-objects was currently a key issue toward their massive use for optoelectronic applications. The observation by photoluminescence of narrow excitonic and biexcitonic emission lines in semiconductor nanowires was usually accepted as evidence for high structural quality. Here, time-resolved cathodoluminescence experiments were performed on isolated ZnO nanobelts grown by chemical vapour deposition. Narrow emission lines were observed at low temperature, together with a clear bi-exciton line. Marked alterations in both the CL intensity and lifetime were observed locally along the nano-object. These were attributed to non-radiative recombination at edge dislocations, closing basal-plane stacking faults, inhomogeneously distributed along the NB length. This led to the conclusion that the observation of narrow excitonic and biexcitonic emission lines was far from sufficient to grade the quality of a nano-object.

Biexciton Emission and Crystalline Quality of ZnO Nano-Objects. P.Corfdir, M.Abid, A.Mouti, P.A.Stadelmann, E.Papa, J.P.Ansermet, J.D.Ganière, B.Deveaud-Plédran: Nanotechnology, 2011, 22[28], 285710