Superlattice hole injection layers for UV LEDs grown on SiC

TitleSuperlattice hole injection layers for UV LEDs grown on SiC
Publication TypeJournal Article
Year of Publication2020
AuthorsZollner, C. J., A. S. Almogbel, Y. Yao, M. Wang, M. Iza, J. S. Speck, S. P. DenBaars, and S. Nakamura
JournalOpt. Mater. Express
Volume10
Pagination2171–2180
Date PublishedSep
KeywordsChemical vapor deposition, Light extraction, Quantum efficiency, Silicon carbide, Ultraviolet light emitting diodes, Ultraviolet radiation
Abstract

AlGaN-based germicidal UV LEDs show promise in fighting the COVID-19 pandemic through disinfection of air, water, and surfaces. We report UV LEDs grown by MOCVD on SiC substrates, fabricated into thin-film flip chip devices. Replacing the uniform p-AlxGa1-xN layer (x $=$ 0.2) with a short-period-superlattice of alternating (x $=$ 0.1 and 0.8) Al-composition improved EQE from 1.3% to 2.7% (3.2% with encapsulation) at 20 A/cm2. Peak EQE and WPE values of 4.8% and 2.8% (287 nm) were measured at current densities below 2 A/cm2, and maximum output power of 7.4 mW (76 mW/mm2) was achieved at 284 nm. Further WPE improvements are expected with both superlattice and uniform layer optimization, improved p-contact metallization, and active region optimization.

URLhttp://www.osapublishing.org/ome/abstract.cfm?URI=ome-10-9-2171
DOI10.1364/OME.398146