InGaN/GaN white light-emitting diodes embedded with europium silicate thin film phosphor

Eun Hong Kim, Kyoung Chan Kim, Dong Ho Kim, Jong Hyeob Baek, Tae Geun Kim

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

This article describes the successful fabrication of europium-silicate thin film phosphor and its application to InGaN/GaN white light-emitting diodes (LEDs) in order to improve the photometric properties of the LEDs, including their correlated color temperatures (CCT) and color rendering index (CRI). The europium-silicate compounds are deposited on GaN templates grown on sapphire substrates by RF-sputtering and then annealed at 1000 °C in an N2 ambient to form a thin film phosphor that produces yellow or red emissions. The thin film phosphor is then patterned with stripes to grow a GaN buffer layer by epitaxially laterally overgrown GaN (ELOG) techniques, on which LED structures are grown by metal organic chemical vapor deposition. The ELOG sample shows no pits on the surface, and the full widths at half maximum (FWHMs) of its X-ray rocking curve for the (002) and (102) planes are as low as 249 and 416 arcsec, respectively. The optical spectrum from the embedded thin film phosphor is adjusted to have a maximum intensity at 560600 nm and a FWHM as wide as 90 nm to make up for the low efficiency at these wavelengths of conventional YAG-based yellow phosphor. Finally, we observed a tristimulus coordinate (x, y)=(0.33, 0.39), CCT=5607 K, and CRI=77.6 from the white LEDs with thin film phosphor as compared with (x, y)=(0.30, 0.28), CCT=8467 K, and CRI=66.52 for the white LEDs without thin film phosphor.

Original languageEnglish
Article number5518521
Pages (from-to)1381-1387
Number of pages7
JournalIEEE Journal of Quantum Electronics
Volume46
Issue number9
DOIs
Publication statusPublished - 2010

Keywords

  • Color rendering indices (CRI)
  • correlated color temperatures (CCT)
  • europium-silicate
  • thin film phosphors
  • white light-emitting diodes (LEDs)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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