Effects of nanostructured photonic crystals on light extraction enhancement of nitride light-emitting diodes
碩士 === 長庚大學 === 光電工程研究所 === 98 === The light extraction efficiency of an InGaN/GaN light-emitting diode (LED) can be enhanced by incorporating nanostructured photonic crystals inside the LED structure. In this paper, we employed plane wave expansion (PWE) method along with finite difference time dom...
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2010
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| Online Access: | http://ndltd.ncl.edu.tw/handle/19766633492780920030 |
| Summary: | 碩士 === 長庚大學 === 光電工程研究所 === 98 === The light extraction efficiency of an InGaN/GaN light-emitting diode (LED) can be enhanced by incorporating nanostructured photonic crystals inside the LED structure. In this paper, we employed plane wave expansion (PWE) method along with finite difference time domain (FDTD) method to reveal the optical confinement effects with the relevant parameters, such as periodicity arrangement and dielectric constant. The results showed that bandgap modulation could increase the efficiency for light extraction with the air-hole periodicity of 200 nm and depth of 200 nm. Focused ion beam (FIB) of Ga was used to create the desired nanostrucured patterns. The technique provides one-step patterning and is adaptable to complicated patterns when compared with other methods. The device micro-PL (photoluminescence) results have demonstrated that the photonic crystal structures could increase the LED peak illumination intensity by 60%. The peak wavelength remained unchanged. As the ratio of the patterned area was optimized to 85%, the peak intensity improvement was further achieved at 90%. A threefold enhancement in the integrated light extraction efficiency was thus accomplished. The experimental details would be presented and discussed.
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