Abstract
We investigated the effect of a mesh-type GaN/SiO2/Al omnidirectional reflector (ODR) on the light output power of AlGaN/InGaN-based ultraviolet (365 nm) LEDs and compared their performance with that of LEDs with a GaN/ITO/Al reflector. Using the scattering matrix method, the normal incidence reflectance was calculated to be 93.7% for the GaN/SiO2 (62 nm)/Al ODR and 79% for the GaN/ITO (30 nm)/Al reflector. The Ag/Ni/Al/Ni (52 nm/10 nm/200 nm/20 nm) contact showed a specific contact resistance of 3.2 × 10−5 Ω cm2 after annealing at 500 °C for 1 min. The forward-bias voltages at 20 mA of LEDs with ODR were in the range of 3.49–3.54 V, which were similar to that of LEDs with an ITO/Al reflector (3.51 V). The LEDs with ODR had series resistances in the range of 14.8–12.5 Ω, whereas the LED with an ITO/Al reflector showed 11.7 Ω. The LEDs with ODR yielded 9.3–19.9% higher light output power at 20 mA than the LED with an ITO/Al reflector. The improved light output power was attributed to the optimization of the high reflectance of the ODR (reflective area) and contact area.
Original language | English |
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Article number | 1600789 |
Journal | Physica Status Solidi (A) Applications and Materials Science |
Volume | 214 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2017 Aug |
Bibliographical note
Publisher Copyright:© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Keywords
- GaN
- SiO
- aluminum
- light extraction
- light-emitting diodes
- omnidirectional reflectors
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry
- Electrical and Electronic Engineering