The Study of the Novel Patterned Sapphire Substrate Applied for Enhancing the Efficiency of the GaN-based Light-emitting Diodes
碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 101 === We use silicon nitride (Si3N4) to replace silicon dioxide (SiO2) as the reflective index-gradient material to fabricate GaN-based patterned sapphire substrate light-emitting diodes. It can not only reduce the threading dislocations densities but also enha...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2013
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| Online Access: | http://ndltd.ncl.edu.tw/handle/46285012141703523611 |
| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 101 === We use silicon nitride (Si3N4) to replace silicon dioxide (SiO2) as the reflective index-gradient material to fabricate GaN-based patterned sapphire substrate light-emitting diodes. It can not only reduce the threading dislocations densities but also enhance the light extraction efficiency (LEE). From the simulation results, the light extraction efficiency enhance approximate 62.7% higher than the PSS-LED. The TEM images show the threading dislocations exist on the trench region and stacking faults produce on the top of the pattern because of the GaN growth laterally. And also we found one threading dislocation which induced from coalescence of GaN thin film on the pattern region only. These evidences prove that the GaN film indeed was grown laterally.
After re-growing, we observed the air voids exist on the top of the textured Si3N4 layer which were due to the GaN epitaxial lateral overgrowth. According to the simulation result, it reveals that the air voids will affect the final luminous efficiency. The luminous efficiency ranking of the four different LEDs is PSN-LED > PSA-LED > PSO-LED > PSS-LED.
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