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Journal of Nanophotonics • Open Access

High performance 380-nm ultraviolet light-emitting-diodes with 3% efficiency droop by using free-standing GaN substrate manufacturing from GaAs substrate
Author(s): Chen-Yu Shieh; Ming-Ta Tsai; Zhen-Yu Li; Hao-Chung Kuo; Jenq-Yang Chang; Gou-Chung Chi; Wei-I Lee

Paper Abstract

We investigated the influence of free-standing GaN (FS-GaN) substrates on the performance of ultraviolet light-emitting-diodes (UV-LEDs) grown on top by atmospheric pressure metal-organic chemical vapor deposition. High-resolution double-crystal x-ray diffraction (HRDCXD) analysis demonstrated high-order satellite peaks and clear fringes between them for UV-LEDs grown on the FS-GaN substrate, from which the interface roughness was estimated. In addition, the full width at half maximum of the HRDCXD rocking curve in the (0002) and the (101¯2) reflections were reduced to below 90 arc sec. The Raman results indicated that the GaN-based epilayer of strain free was grown. Additionally, the effect of the FS-GaN substrate on the crystal quality of the UV-LEDs was examined in detail by transmission electron microscopy (TEM). The TEM characterizations revealed no defects and V-pits were found in the scanned area. Based on the results mentioned above, the light output power of UV-LEDs on the FS-GaN substrate can be enhanced drastically by 80% and 90% at 20 and 100 mA, respectively. Furthermore, an ultralow efficiency degradation of about 3% can be obtained for the UV-LEDs on the FS-GaN substrate at a high injection current. The use of an FS-GaN substrate is suggested to be effective for improving the emission efficiency and droop of UV-LEDs grown thereon.

Paper Details

Date Published: 7 July 2014
PDF: 11 pages
J. Nanophoton. 8(1) 083081 doi: 10.1117/1.JNP.8.083081
Published in: Journal of Nanophotonics Volume 8, Issue 1
Show Author Affiliations
Chen-Yu Shieh, National Central Univ. (Taiwan)
Ming-Ta Tsai, National Chiao Tung Univ. (Taiwan)
Zhen-Yu Li, National Chiao Tung Univ. (Taiwan)
Hao-Chung Kuo, National Chiao Tung Univ. (Taiwan)
Jenq-Yang Chang, National Central Univ. (Taiwan)
Gou-Chung Chi, National Central Univ. (Taiwan)
National Chiao Tung Univ. (Taiwan)
Wei-I Lee, National Chiao Tung Univ. (Taiwan)

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