Light emitting diodes (LEDs) have been fabricated using ensembles of free-standing (In, Ga) N/GaN nanowires (NWs) grown on Si substrates in the self-induced growth mode by molecular beam epitaxy. Electron-beam-induced current analysis, cathodoluminescence as well as biased μ-photoluminescence spectroscopy, transmission electron microscopy, and electrical measurements indicate that the electroluminescence of such LEDs is governed by the differences in the individual current densities of the single-NW LEDs operated in parallel, ie by the inhomogeneity of the current path in the ensemble LED. In addition, the optoelectronic characterization leads to the conclusion that these NWs exhibit N-polarity and that the (In, Ga) N quantum well states in the NWs are subject to a non-vanishing quantum confined Stark effect.
23 Oct 2012
Volume: 23 Issue: 46 Pages: 465301