| Summary: | 碩士 === 元智大學 === 光電工程研究所 === 99 === In this study, silicon nitride is used to replace silicon dioxide as a barrier to form a patterned sapphire substrate. By etching, we obtained the result of a patterned sapphire substrate whose depth is 1181 nm. Besides, there is a fine layer of silicon nitride on the top of the patterns. The refractive index of silicon nitride is 2.05 while that of sapphire is 1.78, and 2.4 for the GaN. Since the refractive index of silicon nitride falls between the GaN and sapphire substrates, silicon nitride can be used as the material for gradient refractive index. However, the refractive index of silicon dioxide is just 1.42, so it is not an useful material for gradient refractive index.
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