  Efficiency droop is a major obstacle facing high-power application of
InGaN/GaN quantum-well (QW) light-emitting diodes. In this letter, we report
the suppression of efficiency droop induced by density-activated defect
recombination in nanorod structure of a-plane InGaN/GaN QWs. In the high
carrier density regime, the retained emission efficiency in a dry-etched
nanorod sample is observed to be over two times higher than that in its parent
QW sample. We further argue that the improvement is a combined effect of the
amendment contributed by lateral carrier confinement and the deterioration made
by surface trapping.
