Core-shell nanorods as ultraviolet light emitting diodes

Cameron, Douglas and Coulon, Pierre-Marie and Fairclough, Simon and Kusch, Gunnar and Edwards, Paul R. and Susilo, Norman and Wernicke, Tim and Kneissl, Michael and Oliver, Rachel A. and Shields, Philip A. and Martin, Robert W. (2023) Core-shell nanorods as ultraviolet light emitting diodes. Nano Letters, 23 (4). 1451–1458. ISSN 1530-6992 (

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Existing barriers to efficient deep ultraviolet (UV) light-emitting diodes (LEDs) may be reduced or overcome by moving away from conventional planar growth and toward three-dimensional nanostructuring. Nanorods have the potential for enhanced doping, reduced dislocation densities, improved light extraction efficiency, and quantum wells free from the quantum-confined Stark effect. Here, we demonstrate a hybrid top-down/bottom-up approach to creating highly uniform AlGaN core-shell nanorods on sapphire repeatable on wafer scales. Our GaN-free design avoids self-absorption of the quantum well emission while preserving electrical functionality. The effective junctions formed by doping of both the n-type cores and p-type caps were studied using nanoprobing experiments, where we find low turn-on voltages, strongly rectifying behaviors and significant electron-beam-induced currents. Time-resolved cathodoluminescence measurements find short carrier liftetimes consistent with reduced polarization fields. Our results show nanostructuring to be a promising route to deep-UV-emitting LEDs, achievable using commercially compatible methods.