Phosphor-free ingan white light emitting diodes using flip-chip technology

Ying Chang Li, Liann Be Chang*, Hou Jen Chen, Chia Yi Yen, Ke Wei Pan, Bohr Ran Huang, Wen Yu Kuo, Lee Chow, Dan Zhou, Ewa Popko

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

11 Scopus citations

Abstract

Monolithic phosphor-free two-color gallium nitride (GaN)-based white light emitting diodes (LED) have the potential to replace current phosphor-based GaN white LEDs due to their low cost and long life cycle. Unfortunately, the growth of high indium content indium gallium nitride (InGaN)/GaN quantum dot and reported LED's color rendering index (CRI) are still problematic. Here, we use flip-chip technology to fabricate an upside down monolithic two-color phosphor-free LED with four grown layers of high indium quantum dots on top of the three grown layers of lower indium quantum wells separated by a GaN tunneling barrier layer. The photoluminescence (PL) and electroluminescence (EL) spectra of this white LED reveal a broad spectrum ranging from 475 to 675 nm which is close to an ideal white-light source. The corresponding color temperature and color rendering index (CRI) of the fabricated white LED, operated at 350, 500, and 750 mA, are comparable to that of the conventional phosphor-based LEDs. Insights of the epitaxial structure and the transport mechanism were revealed through the TEM and temperature dependent PL and EL measurements. Our results show true potential in the Epi-ready GaN white LEDs for future solid state lighting applications.

Original languageEnglish
Article number432
JournalMaterials
Volume10
Issue number4
DOIs
StatePublished - 20 04 2017

Bibliographical note

Publisher Copyright:
© 2017 by the authors.

Keywords

  • InGaN/GaN
  • Phosphor free
  • Quantum dot
  • Quantum well
  • White LED

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