Luminescence mechanism and carrier dynamic studies of InGaN-based dichromatic light emitting diodes with ultraviolet and blue emissions

Shih Wei Feng, Li Wei Tu, Jen Inn Chyi, Hsiang Chen Wang

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

In this study, to investigate the luminescence mechanism and carrier dynamics of dichromatic InGaN-based light emitting diodes (LEDs) with two active regions, an ultraviolet (UV)-blue LED (UV active region above the blue one) and a blue-UV LED (blue active region above the UV one) were prepared. Photoluminescence (PL), cathodoluminescence (CL), and time-resolved photoluminescence measurements were performed. For the PL spectra of both LEDs, the blue emissions are stronger than the UV emissions. This trend shows that the higher degree of carrier localization of the blue active region, in either the upper or lower portions of the LEDs, can enhance carrier capture and recombination efficiency. Due to the large and bright light spots emitted from indium-rich clusters in the blue active region, CL images showed that the blue emission is dominant in the image shape for both samples. Furthermore, it was shown that the optical properties and carrier dynamics of dichromatic InGaN-based LEDs could be well explained by the combined effects of the carrier localization effect, structures, extraction efficiency, defect density, and carrier capture efficiency in the UV and blue active regions. Also, thermal effect plays an important role in carrier transport behavior in such dichromatic LEDs. The research results provide important information for operation mechanisms and device designs of dichromatic LEDs.

Original languageEnglish
Pages (from-to)909-915
Number of pages7
JournalThin Solid Films
Volume517
Issue number2
DOIs
StatePublished - 28 Nov 2008

Keywords

  • Carrier dynamics
  • Carrier localization
  • Carrier transport
  • Cathodoluminescence
  • Dichromatic light emitting diodes
  • Extraction efficiency
  • Time-resolved photoluminescence
  • White light emitting diodes

Fingerprint

Dive into the research topics of 'Luminescence mechanism and carrier dynamic studies of InGaN-based dichromatic light emitting diodes with ultraviolet and blue emissions'. Together they form a unique fingerprint.

Cite this