Photonic crystals (PhCs) were typically fabricated on the light emitting surface of light emitting diodes (LEDs) to improve light extraction, which is regarded as the weak coupling between the laterally propagated light in the epi-layers and the surface nanostructure. This work demonstrates GaN-based LEDs with the PhC structure on the mesa surface and nanohole arrays surrounding the light emitting mesa. Our new device (SHLED) shows a 56% higher optical output power than the planar structure (PLED), as compared with the 40% improvement of the surface PhC device (SLED) over PLED. The output power of SHLED is higher than that of SLED due to the enhanced diffraction of low order modes propagated in the lateral direction, in addition to the higher order mode light diffraction from the surface PhCs. From the relative angular spectra, the interaction of in-plane optical wave with the nanoholes (which are etched through MQWs) is much stronger than that with surface PhCs, suggesting an efficient light diffraction to the surface normal by nanoholes.

Date Published: 15 October 2012
PDF: 6 pages
Proc. SPIE 8484, Twelfth International Conference on Solid State Lighting and Fourth International Conference on White LEDs and Solid State Lighting, 84840M (15 October 2012); doi: 10.1117/12.929188

Published in SPIE Proceedings Vol. 8484:
Twelfth International Conference on Solid State Lighting and Fourth International Conference on White LEDs and Solid State Lighting
Matthew H. Kane; Christian Wetzel; Jian-Jang Huang; Ian T. Ferguson, Editor(s)