High performance 380-nm ultraviolet light-emitting-diodes with 3% efficiency droop by using free-standing GaN substrate manufacturing from GaAs substrate

Chen Yu Shieh, Ming Ta Tsai, Zhen Yu Li*, Hao-Chung Kuo, Jenq Yang Chang, Gou Chung Chi, Wei-I Lee

*Corresponding author for this work

Research output: Contribution to journalArticle

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 (101̄2) 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.

Original languageEnglish
Article number083081
JournalJournal of Nanophotonics
Volume8
Issue number1
DOIs
StatePublished - 1 Jan 2014

Keywords

  • atmospheric pressure metal-organic chemical vapor deposition
  • efficiency droop
  • free-standing GaN substrate
  • high-resolution double crystal x-ray diffraction
  • light output power
  • transmission electron microscopy
  • ultraviolet light-emitting-diodes

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