Abstract
We report on the realization of top-down fabricated, electrically driven, deep-ultraviolet (DUV) AlGaN micropillar array light emitting diodes (LEDs) with high output power density. Ordered arrays of micropillars with the inverse-taper profile were formed from an AlGaN epitaxial stack (epistack) using a Ni-masked Cl2 plasma dry etch and KOH-based wet etching. Following deposition of the n-contact, polydimethylsiloxane was spin-coated and etched-back to reveal the tips of the pillars to allow for formation of the p-contact. The DUV LEDs were tested at the wafer-level using a manual probe station to characterize their electrical and optical properties, revealing stable electroluminescence at 286 nm with a narrow 9-nm linewidth. Optical output power was found to be linearly related to current density, with output power densities up to 35 mW/cm2, comparable to the results reported for epitaxially grown DUV nanowire LEDs. Simulations revealed that the inverse-taper profile of the micropillars could lead to large enhancements in light extraction efficiency (ηEXT) of up to 250% when compared to micropillars with vertical sidewalls. The realization of ordered, electrically driven, top-down fabricated micropillar DUV LEDs with competitive output power represents an important step forward in the development of high-efficiency, scalable DUV emitters for a wide range of applications.
Highlights
D scitation.org/journal/adv other microstructures have been found to be the most effective at enhancing ηEXT
The vast majority of studies involving AlGaN-based DUV nanowire/microstructure light emitting diodes (LEDs) have focused on epitaxial nanowires grown using metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) in a “bottom-up” fabrication process
We demonstrate the fabrication and characterization of top-down fabricated, electrically driven DUV micropillar array LEDs emitting at 286 nm with a narrow, 9 nm linewidth and output power densities up to 35 mW/cm2, comparable to epitaxially grown DUV nanowire LEDs
Summary
D scitation.org/journal/adv other microstructures have been found to be the most effective at enhancing ηEXT.
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