We study the nature of excitons bound to I1 basal plane stacking faults in ensembles of ultrathin GaN nanowires by continuous-wave and time-resolved photoluminescence spectroscopy. These ultrathin nanowires, obtained by the thermal decomposition of spontaneously formed GaN nanowire ensembles, are tapered and have tip diameters down to 6 nm. With decreasing nanowire diameter, we observe a strong blue shift of the transition originating from the radiative decay of stacking fault-bound excitons. Moreover, the radiative lifetime of this transition in the ultrathin nanowires is independent of temperature up to 60 K and significantly longer than that of the corresponding transition in as-grown nanowires. These findings reveal a zero-dimensional character of the confined exciton state and thus demonstrate that I1 stacking faults in ultrathin nanowires act as genuine quantum dots.
@article{arxiv.1601.01162,
title = {Crystal-phase quantum dots in GaN quantum wires},
author = {P. Corfdir and C. Hauswald and O. Marquardt and T. Flissikowski and J. K. Zettler and S. Fernández-Garrido and L. Geelhaar and H. T. Grahn and O. Brandt},
journal= {arXiv preprint arXiv:1601.01162},
year = {2016}
}