Core-shell multi-quantum wells in ZnO/ZnMgO nanowires with high optical efficiency at room temperature

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))Mg(x)O core-shell quantum well heterostructures grown by metal organic vapor phase epitaxy. Varying the barrier Mg concentration from x = 0.15 to 0.3 leads to the formation of misfit induced dislocations in the multi-quantum wells. Correlatively, temperature dependent 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 10 K intensity is retained at room temperature with x = 0.15, against 1% with x = 0.30. These results open the way to the realization of high optical efficiency nanowire-based light-emitting diodes.