Open AccessDevelopment of high performance green c-plane III-nitride light-emitting diodes
Author(s) -
Abdullah I. Alhassan,
Nathan G. Young,
Robert M. Farrell,
Christopher D. Pynn,
Feng Wu,
Ahmed Y. Alyamani,
Shuji Nakamura,
Steven P. DenBaars,
James S. Speck
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.005591
Subject(s) - light emitting diode , materials science , optoelectronics , quantum efficiency , diode , quantum well , nitride , active layer , layer (electronics) , barrier layer , wide bandgap semiconductor , optics , nanotechnology , physics , laser , thin film transistor
The effect of employing an AlGaN cap layer in the active region of green c-plane light-emitting diodes (LEDs) was studied. Each quantum well (QW) and barrier in the active region consisted of an InGaN QW and a thin Al 0.30 Ga 0.70 N cap layer grown at a relatively low temperature and a GaN barrier grown at a higher temperature. A series of experiments and simulations were carried out to explore the effects of varying the Al 0.30 Ga 0.70 N cap layer thickness and GaN barrier growth temperature on LED efficiency and electrical performance. We determined that the Al 0.30 Ga 0.70 N cap layer should be around 2 nm and the growth temperature of the GaN barrier should be approximately 75° C higher than the growth temperature of the InGaN QW to maximize the LED efficiency, minimize the forward voltage, and maintain good morphology. Optimized Al 0.30 Ga 0.70 N cap growth conditions within the active region resulted in high efficiency green LEDs with a peak external quantum efficiency (EQE) of 40.7% at 3 A/cm 2 . At a normal operating condition of 20 A/cm 2 , output power, EQE, forward voltage, and emission wavelength were 13.8 mW, 29.5%, 3.5 V, and 529.3 nm, respectively.