  Nanowire-based light-emitting devices require multi-quantum well
heterostructures with high room temperature optical efficiencies. We
demonstrate that such efficiencies can be attained through the use of
ZnO/Zn(1-x)MgxO core shell quantum well heterostructures grown by metal organic
vapour phase epitaxy. Varying the barrier Mg concentration from x=0.15 to x=0.3
leads to the formation of misfit induced dislocations in the multi quantum
wells. Correlatively, temperature dependant photoluminescence reveals that the
radial well luminescence intensity decreases much less rapidly with increasing
temperature for the lower Mg concentration. Indeed, about 54% of the 10K
intensity is retained at room temperature with x=0.15, against 2% with x=0.30.
Those results open the way to the realization of high optical efficiency
nanowire-based light emitting diodes.
