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Proceedings Paper

Low-temperature electroluminescent behaviors of InGaN/GaN-based nanorod light emitting diode arrays
Author(s): Liang-Yi Chen; Chun-Hsiang Chang; Ying-Yuan Huang; JianJang Huang
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Paper Abstract

For InGaN/GaN based nanorod devices using top-down etching process, the optical output power is affected by non-radiative recombination due to sidewall defects (which decrease light output efficiency) and mitigated quantum confined Stark effect (QCSE) due to strain relaxation (which increases internal quantum efficiency). Therefore, the exploration of low-temperature optical behaviors of nanorod light emitting diodes (LEDs) will help identify the correlation between those two factors. In this work, low-temperature EL spectra of InGaN/GaN nanorod arrays was explored and compared with those of planar LEDs. The nanorod LED exhibits a much higher optical output percentage increase when the temperature decreases. The increase is mainly attributed to the increased carriers and a better spatial overlap of electrons and holes in the quantum wells for radiative recombination. Next, while the nanorod array shows nearly constant peak energy with increasing injection currents at the temperature of 300K, the blue shift has been observed at 190K. The results suggest that with more carriers in the quantum wells, carrier screening and band filling still prevail in the partially strain relaxed nanorods. Moreover, when the temperature drops to 77K, the blue shift of both nanorod and planar devices disappears and the optical output power decreases since there are few carriers in the quantum wells for radiative recombination.

Paper Details

Date Published: 23 September 2011
PDF: 6 pages
Proc. SPIE 8123, Eleventh International Conference on Solid State Lighting, 81230T (23 September 2011); doi: 10.1117/12.893534
Show Author Affiliations
Liang-Yi Chen, National Taiwan Univ. (Taiwan)
Chun-Hsiang Chang, National Taiwan Univ. (Taiwan)
Ying-Yuan Huang, National Taiwan Univ. (Taiwan)
JianJang Huang, National Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 8123:
Eleventh International Conference on Solid State Lighting
Matthew H. Kane; Christian Wetzel; Jian-Jang Huang, Editor(s)

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