Far-field of GaN film-transferred green light-emitting diodes with two-dimensional photonic crystals

Opt Express. 2009 May 25;17(11):8795-804. doi: 10.1364/oe.17.008795.

Abstract

Far-field distributions of GaN-based photonic crystal (PhC) film-transferred light-emitting diodes (FT-LEDs) were investigated. The thickness of the device is about 840 nm. The emission wavelength is around 520 nm. The PhC region is a square lattice with a/lambda around 0.5. Angular-resolved measurements in the Gamma-X and Gamma-M directions were made in the polarized-resolved manner. Guided mode extraction behavior in agreement with the two-dimensional free-photon band calculation was observed. In addition, the pseudo-TM behavior for the non-collinearly coupled modes was observed. The azimuthal-mapping of the angular-resolved spectra revealed the evolution of the collinearly and the non-collinearly coupled modes. Furthermore, the light enhancement of approximately 2.7x and the collimation angle about 102.3 degrees were achieved.

MeSH terms

  • Color
  • Crystallization / methods
  • Gallium / chemistry*
  • Lighting / instrumentation*
  • Materials Testing
  • Membranes, Artificial*
  • Photons
  • Semiconductors*

Substances

  • Membranes, Artificial
  • gallium nitride
  • Gallium