UV LEDs Based on p-i-n Core-Shell AlGaN/GaN Nanowire Heterostructures Grown by N-polar Selective Area Epitaxy

Published

March 20, 2019

Author(s)

Matthew Brubaker, Kristen Genter, Alexana Roshko, Paul T. Blanchard, Bryan T. Spann, Todd E. Harvey, Kris A. Bertness

Abstract

Ultraviolet light-emitting diodes (UV LEDs) fabricated from N-polar AlGaN/GaN core-shell nanowires with p-i-n structure produced electroluminescence at 365 nm with 5x higher intensities than similar GaN homojunction LEDs. The improved characteristics were attributed to localization of spontaneous recombination to the nanowire core, reduction of carrier overflow losses through the nanowire shell, and elimination of current shunting. Poisson-drift-diffusion modeling indicated that a shell Al mole fraction of x=0.1 in AlxGa1-xN effectively confines electrons and injected holes to the GaN core region. AlGaN overcoat layers targeting this approximate Al mole fraction were found to possess a low-Al-content tip and high-Al-content shell, as determined by scanning transmission electron microscopy. Photoluminescence spectroscopy further revealed the actual Al mole fraction to be nanowire diameter dependent, where the tip and shell compositions converged towards the nominal flux ratio for large- diameter nanowires.

Citation

Nanotechnology

Volume

30

Issue

23

Pub Type

Journals

Download Paper

https://doi.org/10.1088/1361-6528/ab07ed

Local Download

Keywords

GaN, Nanowires, LEDs, Core-shell, Selective Area Epitaxy

Citation

Brubaker, M. , Genter, K. , Roshko, A. , Blanchard, P. , Spann, B. , Harvey, T. and Bertness, K. (2019), UV LEDs Based on p-i-n Core-Shell AlGaN/GaN Nanowire Heterostructures Grown by N-polar Selective Area Epitaxy, Nanotechnology, [online], https://doi.org/10.1088/1361-6528/ab07ed, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=927132 (Accessed April 26, 2024)