- 學位論文
以脈衝雷射蒸鍍法成長氧化鋅奈米結構及其特性之研究
Growth and Characterization of ZnO Nanostructures by Pulsed Laser Deposition
摘要
脈衝雷射蒸鍍法(pulsed laser deposition, PLD)被廣泛地用來製作各種高品質 的氧化物薄膜。本論文利用PLD，在較高的氣氛壓力下，以無催化劑輔助方式 成長氧化鋅(ZnO)奈米結構。藉由改變成長的條件，如氣體種類及壓力、基板 溫度、雷射能量、成長時間、基板到靶材之間的距離以及採用不同的基板，可 以改變ZnO 奈米結構的形式及光學特性。我們發現在氧氣跟氦氣流量各為10 sccm，總壓力為5 Torr 下可以形成垂直於基板的ZnO 奈米柱，其直徑為250∼ 300 nm、長度約1 μm 左右，且奈米柱頂端為錐狀。室溫PL 光譜分析發現這 些ZnO 奈米柱具有良好的發光特性。而在純氦氣氛中，其壓力為1 Torr 下所生 成的ZnO 奈米結構為島狀結構，由正面圖觀察出形狀為六角形錐狀，其島狀物 直徑約在90∼110 nm 之間，且可觀察到島狀結構頂端有成長出直徑約28 nm 左 右的短奈米線。此外，藉由適當地調整生長參數或製程，我們也能以PLD 製作出 其他特殊的奈米結構，例如類似奈米花、奈米樹枝狀結構等等。
並列摘要
Pulsed laser deposition (PLD) is widely used to synthesize various high-quality oxide thin films. In this study, ZnO nanostructures were grown by PLD without the use of catalyst under relatively high ambient pressures. The forms and optical properties of the ZnO nanostructures can be modified by adjusting the growth parameters, such as the types and pressures of the ambient gases, the substrate temperature, the growth time, the target-substrate distance, and the substrate used. We found that vertical ZnO nanorods with c axes perpendicular to the substrate can be grown in 5 Torr ambient of mixed oxygen and helium, both flowing at 10 sccm. The diameter and length of these nanorods were 250 – 300 nm and ~ 1μm, respectively, and the tops of the rods were pyramid-like. Photoluminescence spectra measured at room temperature showed good emission properties of these nanorods. On the other hand, hexagonal ZnO islands with sizes ranging from 90 to 110 nm were formed under 1 Torr pressure of pure helium. Short nanorods with diameter ~ 30 nm were observed to grow on the tops of some islands. Moreover, by suitably adjusting the growth conditions and processes, we have also fabricated flower-like and branch-like ZnO nanostructures by PLD.