Quenching of the luminescence intensity of GaN nanowires under electron   beam exposure: Impact of C adsorption on the exciton lifetime
  Electron irradiation of GaN nanowires in a scanning electron microscope strongly reduces their luminous efficiency as shown by cathodoluminescence imaging and spectroscopy. We demonstrate that this luminescence quenching originates from a combination of charge trapping at already existing surface states and the formation of new surface states induced by the adsorption of C on the nanowire sidewalls. The interplay of these effects leads to a complex temporal evolution of the quenching, which strongly depends on the incident electron dose per area. Time-resolved photoluminescence measurements on electron-irradiated samples reveal that the carbonaceous adlayer affects both the nonradiative and the radiative recombination dynamics. 
Jonas L\"ahnemann, Timur Flissikowski, Martin W\"olz, Lutz Geelhaar,   Holger T. Grahn, Oliver Brandt and Uwe Jahn
cond-mat.mes-hall cond-mat.mtrl-sci