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Improved light output power of GaN‐based ultraviolet light‐emitting diode using a mesh‐type GaN/SiO 2 /Al omnidirectional reflector
Author(s) -
Won JunYoun,
Kim DaeHyun,
Kang Daesung,
Sung JunSuk,
Kim DaSom,
Kim SunKyung,
Seong TaeYeon
Publication year - 2017
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201600789
Subject(s) - light emitting diode , materials science , optoelectronics , reflector (photography) , optics , diode , distributed bragg reflector , wavelength , light source , physics
We investigated the effect of a mesh‐type GaN/SiO 2 /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/SiO 2 (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 cm 2 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.