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12/21 專題演講公告

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演講題目Direct Growth of Flexible GaN Film via van der Waals Epitaxy




國立清華大學材料科學與工程學系學士 (2006)

美國加州大學洛杉磯分校材料科學與工程學系博士 (2010)




美國布魯克海文國家實驗室電子顯微鏡組客座科學家 (2012/5-2012-8)

IBM華生研究中心物理科學部博士後研究員 (2010-2012)


演講摘要 A flexible gallium nitride thin film was obtained on mica through van der Waals epitaxy. A hydride vapor phase epitaxy was applied to fabricate such flexible GaN thin film directly on substrate suing an optimized two-step growing process to form LT-GaN and HT-GaN sequentially. The interfacial stress caused by the mismatches of thermal expansion coefficient and lattice were significantly reduced via van der Waals epitaxy and the proposed two-step growth. A critical (minimum) growth pressure was found to grow the HT-GaN. The optical performance was controlled by interface and surface roughness. For poor-quality LT-GaN, it quickly decomposed during HT-GaN growth and induced high density of defects near the LT-GaN/HT-GaN interface. The defects then caused the GaN film non-transparent. The surface roughness also controlled the transmittance. In the measurement region, the average transmittance decreased linearly as the GaN surface became rougher. A reliability test was approached where the strong bending caused slight PL peak shift, but did not significantly reduced the peak intensity. Thus, such direct grown GaN film on F-mica substrate can be evaluated as a reliable optical device.