  Recently, we suggested an unconventional approach [the so-called
Internal-Field-Guarded-Active-Region Design (IFGARD)] for the elimination of
the crystal polarization field induced quantum confined Stark effect (QCSE) in
polar semiconductor heterostructures. And in this work, we demonstrate by means
of micro-photoluminescence techniques the successful tuning as well as the
elimination of the QCSE in strongly polar $[000\bar{1}]$ wurtzite GaN/AlN
nanodiscs while reducing the exciton life times by more than two orders of
magnitude. The IFGARD based elimination of the QCSE is independent of any
specific crystal growth procedures. Furthermore, the cone-shaped geometry of
the utilized nanowires (which embeds the investigated IFGARD nanodiscs)
facilitates the experimental differentiation between quantum confinement- and
QCSE-induced emission energy shifts. Due to the IFGARD, both effects become
independently adaptable.
