氧化鋅與石墨烯材料成長機制與特性研究;Growth mechanism and characterizations of graphene and ZnO nanostructure

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/54273

Title:	氧化鋅與石墨烯材料成長機制與特性研究;Growth mechanism and characterizations of graphene and ZnO nanostructure
Authors:	陳重維;Chen,Chung-Wei
Contributors:	物理研究所
Keywords:	氧化鋅;石墨烯;化學氣相沈積法;ZnO Graphene CVD
Date:	2012-08-24
Issue Date:	2012-09-11 18:41:22 (UTC+8)
Publisher:	國立中央大學
Abstract:	在本論文，我們將研究以化學氣相沈積法在不同方向性的基板上成長出a, c, m三種不同方向性之氧化鋅薄膜及氧化鋅奈米線。沿c軸成長之氧化鋅薄膜，其光激螢光光譜數據顯示隨著氧化鋅薄膜厚度從0.4um增加到1.3um, 其光激螢光光譜峰值將由3.3eV藍移到3.26eV。光激螢光光譜訊號藍移原因是氧化鋅薄膜厚度薄其晶格應力越大，這也同時由XRD數據證實氧化鋅薄膜的晶格受應力壓縮。在非極性的氧化鋅材料成長方面，我們利用非極化的a-plane 氮化鎵基版成長出單晶非極性之a-plane 氧化鋅奈米線，由SEM結果判斷，因為a-plane氧化鋅奈米線延著(110)方向成長，所以a-plane氧化鋅奈米線和基版夾角為30度, 從a-plane奈米線表面形貌分析其成長機制為vw 模式。與c-plane 氧化鋅奈米線的ＳＫ模式不同，推測其原因是 a-plane的自由能較低。我們同時在m-plane p型氮化鎵基版上成長出n型氧化鋅薄膜，並將其做成非極性異質接面發光二極體。其電激螢光發光波長為458奈米，且在不同電流（10，20，40mA）的注入下，其發光波長並未產生紅移或藍移現象。在石墨烯的成長方面，我們藉由調控CH4的流量與成長時間控制，可以得到單層碳原子所組成的石墨烯或者是多層石墨烯。在應用方面，因為石墨烯的疏水性造成金屬與石墨烯的接觸電阻極大。我們利用臭氧清潔石墨烯表面，使接觸電阻降低為千分之一。另外，利用石墨烯接觸面積大的特性，我們成功制備出以單層石墨烯為反應層的氧氣偵測器，在低於500ppm的氧濃度情況下，仍可以發現明顯的電流變化。In this thesis, we will discuss ZnO material with different orientation grown on various substrates and graphene grown on copper foil by home-made atmospheric pressure chemical vapor deposition. For c-plane ZnO films growth, the thin films were grown on c-plane GaN templates. The surface morphology of ZnO film depended on growth temperature and growth time. From photoluminescence (PL) spectrum, near band edge peak suggest that the film stress could be responsible for the blue shift, which corresponding to the XRD results. For the a-plane ZnO nanowires growth, the ZnO nanowires were grown on a-plane GaN templates without employing any catalyst. The growth mechanism on a-GaN was the Volmer-Weber (VW) mode and differed from the Stranski-Krastanow (SK) mode observed for growth on c-GaN. This difference results from the higher interfacial free-energy on the a-plane between ZnO and GaN than that on the c-plane orientation. m-plane ZnO thin film were successfully grown on m-plane p-GaN and be fabricated a heterosturctured light emitting diodes. I-V measurement result shows the turn on voltage was 6 volt and the electroluminescent emission peak was at 458 nm in room temperature with different injected current. Monolayer and few-layer of high-quality graphene have been grown on copper foils with different H2/ CH4 gas ratio by chemical vapor deposition at 17torr. The combination of UV ozone exposure prior to metal contact deposition and annealing of the contacts produces minimum specific contact resistances values of 7x10-7 Ω-cm2 for Ti/Au on graphene layers on SiO2/Si substrates. This is an attractive option for cleaning the graphene surface without issues related to energetic ions in O2 plasma exposures. For application, graphene sensor showed rapid change in the current when exposed to different O2 concentration ambient at room temperature. These results show the potential of graphene for O2 sensing applications.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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