Open AccessEffects of optimized contact scheme on the performance of high-power GaN-based light-emitting diodes
Author(s) -
Jianming Zhang,
Deshu Zou,
Chen Xu,
Xiuquan Gu,
Shen Guang-di
Publication year - 2007
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.56.6003
Subject(s) - materials science , light emitting diode , optoelectronics , contact resistance , joule heating , current (fluid) , diode , saturation current , voltage , gallium nitride , layer (electronics) , optics , nanotechnology , composite material , electrical engineering , physics , engineering
Due to the lateral current transport in the mesa-structure GaN based LEDsthe resistance of the n-type material of the GaN and lower confinement layer is not negligible for large area and high applied current density applieationswhich causes the current spreading nonuniformly along the lateral direction. With an optimized contact scheme to reduce the length for the lateral current transporttwo different kinds of contact schemes of high-power GaN-based flip-chip LEDs (FCLEDs) are fabricated. It is shown that the forward voltage of this FCLED with interdigitated contact scheme is 3.35V at forward current 350mAand exceeds that of FCLEDs with optimized ring-shaped interdigitated contact scheme by 0.15V. Although the light emitting area of FCLEDs with optimized ring-shaped interdigitated contact scheme is slightly smaller than that of FCLEDs with interdigitated contact schemeit is found that the light output from the former is larger than that from the later at higher injection currents. Furthermorethe light output from the FCLEDs with optimized ring-shaped interdigitated contact scheme saturates slowly at higher injection currents as compared to the FCLEDs with interdigitated contact schemeindicating that the saturation behavior of the FCLEDs with interdigitated contact scheme is more pronounced. It is confirmed that an optimized contact schemewhich leads to the more uniform current spreadingcan decrease joule heat generated and considerably improve the electrical and optical characteristics of the FCLEDs.