S.S KAO
Outline
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Introduction
Experiment
Results and discussion
Conclusion
References
Introduction
• The efficiency droop is still a serious restriction for highpower applications.The physical origin of droop including
carrier delocalization, Auger recombination, poor hole
injection, and electron leakage have been reported. Among
them, the insufficient hole injection and electron leakage may
play an important role.
Introduction
• The AlGaN electron-blocking layer (EBL) acting as a potential
barrier for holes may also obstruct the holes from injecting
into the active region. Consequently, the holes were majorly
distributed in the last QW next to p-type region.
• The usage of AlGaN barriers has also been suggested because
it provides a better capability of carrier confinement for the
wider band-gap of AlGaN than GaN and a relatively smaller
polarization in the last-barrier/EBL interface with a weakened
band-bending of EBL, which is a benefit for the hole injection.
Introduction
• The larger polarization mismatch between InGaN wells and
AlGaN barriers will cause a severe tilting of energy band and
thereby degrade the hole transportation between QWs. Thus,
the hole distribution and LED performance does not benefit
much from the employment of AlGaN barriers.
• In this letter, we propose that the quantum barriers are
modified by alternating AlGaN barriers with GaN barriers
along the growth direction in MQWs for better LED
performance, which is referred as the alternating quantum
barriers.
Experiment
Results and discussion
Results and discussion
Results and discussion
Conclusion
• In conclusion, InGaN LEDs with special modifications for the
quantum barriers by alternating AlGaN barriers with GaN
barriers are proposed. Simulation shows that the electron
confinement and hole injection/transportation are efficiently
improved, and the electron leakage is reduced accordingly in
the proposed structure, due to the appropriate band enginThe
IQE and efficiency droop are therefore largely improved, as
compared to the counterparts with GaN barriers or AlGaN
barriers. Moreover, the increase of Al composition on the basis
of our designed structure can further promote the LED
performance because of the more uniform carrier distribution.
References
• Yujue Yang and Yiping “ZengEfficiency Droop Reduction in
InGaN LEDs by Alternating AlGaN Barriers With GaN
Barriers”
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