Application of Nanosphere Lithography to LED Surface Texturing and to the Fabrication of Nanorod LED Arrays

In this study, the process of nanosphere lithography was developed and applied to LED surface texturing and nanorod device fabrication. We observed a texture-size-dependent improvement of total light output. While the increase of output optical power from the textured LEDs can be attributed to surfa...

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Bibliographic Details
Published in:IEEE journal of selected topics in quantum electronics 2009-07, Vol.15 (4), p.1242-1249
Main Authors: Ke, Min-Yung, Wang, Cheng-Yin, Chen, Liang-Yi, Chen, Hung-Hsien, Chiang, Hung-Li, Cheng, Yun-Wei, Hsieh, Min-Yann, Chen, Cheng-Pin, Huang, JianJang
Format: Article
Language:English
Subjects:
Arrays
Cylinders
Devices
LEDs
Light emitting diodes
Lithography
Nanocomposites
Nanomaterials
nanorods
Nanoscale devices
nanosphere lithography
Nanostructure
Optical device fabrication
Optical devices
Optical scattering
Optical surface waves
Rough surfaces
Semiconductors
Surface roughness
Surface texture
Texturing
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Summary:In this study, the process of nanosphere lithography was developed and applied to LED surface texturing and nanorod device fabrication. We observed a texture-size-dependent improvement of total light output. While the increase of output optical power from the textured LEDs can be attributed to surface roughening in the GaN-air surface and to the increase of internal quantum efficiency as the strain is relaxed with the surface texturing, the size-dependent device performance is related to the interaction of generated photons with the textured surface. We further etched through the p-GaN and quantum well region to form p-i-n nanorods on the sample. By inserting a spacer to prevent p-type contact from shorting the n-GaN, we successfully demonstrated nanorod LED arrays. For such a device, a narrower radiation profile was demonstrated from the nanorod LED array as compared with that from the planar LED. The result is associated with the vertical guiding effect along the nanorod cylinder and the Bragg scattering of photons extracted from the sidewall by the rest of the rods. Furthermore, the electroluminescence spectra showed a nearly constant peak wavelength of the nanorod LED arrays, which is due to the suppression of the effect of quantum confined Stark effect.
ISSN:1077-260X
1558-4542
DOI:10.1109/JSTQE.2009.2016433