Sandia Corporation

Philips Lumileds Lighting Company LLC

Lumileds Holding B.v.

Jonathan Wierer

Andrew A Allerman

Ines Montano

Mihail M Sigalas

Michael R Krames

Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al&#x3e;0.3, thinner QW layers (&#x3c;2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

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Albuquerque, NM, United States of America

Jonathan Wierer