  Polarization engineered interband tunnel junctions (TJs) are integrated in
nanowire ultraviolet (UV) light emitting diodes (LEDs). A ~6V reduction in
turn-on voltage is achieved by the integration of tunnel junction at the base
of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into
the nanowire LEDs leads to suppressed efficiency droop in TJ integrated
nanowire LEDs. The combination of both reduced bias voltage and increased hole
injection increases the wall plug efficiency in these devices. More than 100
microwatts of UV emission at ~310 nm is measured with external quantum
efficiency in the range of 4 - 6 m%. The realization of tunnel junction within
the nanowire LEDs opens a pathway towards the monolithic integration of
cascaded multi-junction nanowire LEDs on silicon.
