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High extraction efficiency ultraviolet light-emitting diode

Patent ·
OSTI ID:1226807
; ;
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>0.3, thinner QW layers (<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.
Research Organization:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC04-94AL85000
Assignee:
Sandia Corporation (Albuquerque, NM)
Patent Number(s):
9,196,788
Application Number:
14/480,072
OSTI ID:
1226807
Country of Publication:
United States
Language:
English

References (14)

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Extremely weak surface emission from (0001) c-plane AlGaN multiple quantum well structure in deep-ultraviolet spectral region journal August 2006
Strain-driven light-polarization switching in deep ultraviolet nitride emitters journal July 2011
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Optical anisotropy in [0001]-oriented Al x Ga 1 − x N / AlN quantum wells ( x > 0.69 ) journal March 2009
Valence band engineering for remarkable enhancement of surface emission in AlGaN deep-ultraviolet light emitting diodes journal May 2008
Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers journal September 2010

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