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Influence of various activation temperatures on
the optical degradation of Mg doped InGaNGaN
MQW blue LEDs
C.J. Youn, T.S. Jeong, M.S. Han, J.W. Yang, K.Y. Lim, H.W. Yu
Journal of Crystal Growth
J. K. Lee
Outline
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Abstract
Introduction
Experiment
Results and Discussion
Conclusion
References
Introduction
 We have grown the GaN-based InGaN/GaN MQW blue LED by
MOCVD method and investigated the optical performance
degradation of InGaN/GaN MQW LED structure as a function
of the Mg-doped GaN layer activation temperature using
photoluminescence, electroluminescence , and current–voltage
measurements.
 The turn on voltage of blue LED is 2.56V and the forward
voltage measured at 20mA is 3.5 V, which were obtained from
the best LED.
Experiment
In0.15Ga0.85N ?
Schematic diagram of InGaN/GaN MQW LED structure. The cross-sectional TEM image
shows the active layer consisting of six pairs of InGaN/GaN layers.
Results and Discussion
463.6nm
454.5nm
476.9nm
491.1nm
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Photoluminescence spectrum of the as-grown InGaN/GaN MQW LED structure. This
spectrum was resolved into individual peaks by using a multi-Gaussian fitting (dot
line). The peaks at 476.9 and 491.1nm were found to be the LO phonon replicas.
Results and Discussion
476.9nm
491.1nm
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Photoluminescence spectra obtained from the InGaN/GaN MQW LED structures with
the Mg-doped p-GaN layer activated at the temperatures range from 750℃ to 925℃ for
30 s in a N2 ambient.
Results and Discussion
Barrier
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Well
The cross-sectional HRTEM image for the active layer of InGaN/GaN MQW
annealed at 825℃ for 30 s.
Results and Discussion
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Electroluminescence spectra obtained from the InGaN/GaN MQW LEDs with the Mg-doped
p -GaN layer activated at various annealing temperatures. The LO phonon replicas was also
appeared in the electroluminescence spectrum.
Results and Discussion
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The peak intensities of the PL and EL obtained from the InGaN/GaN MQW LED
structures activated at various Mg activation temperatures. The PL intensity of the asgrown InGaN/GaN MQW structure is inserted for a comparison.
Results and Discussion
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The forward I–V characteristics of the InGaN/GaN MQW LED with the p-GaN layer
activated at 825℃.
Results and Discussion
3.61V
3.5V
825℃
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The forward voltage and the out power obtained from the InGaN/GaN MQW blue LED as a
function of the Mgdoped p-GaN layer activation temperature.
Conclusion
 As the Mg activation temperature increase, the optical properties
of the LED tended to decrease.
 With increasing the Mg activation temperature of P-GaN layer,
the optical properties of the LED structure tended to significantly
degrade.
 These results imply that the special techniques have to be
developed to make a Mg-doped p-GaN layer activate at lower
temperature than the routinely accepted temperature range of
800–9001C to obtain the best optical performance of the
InGaN/GaN MQW blue LEDs.
References
 C.J. Youn, T.S. Jeong, M.S. Han, J.W. Yang, K.Y. Lima, H.W. Yu ”
Influence of various activation temperatures on the optical
degradation of Mg doped InGaN/GaN MQW blue LEDs ”
Journal of Crystal Growth 250 (2003) 331–338.