利用電漿輔助式分子束磊晶系統和微波合成成長氧化鋅磊晶層和奈米粉末

ZnO Epilayers and Nano-particals Grown by PA-MBE and Microwave-assisted Synthesis

余筱君(Hsiao-Chun Yu)

指導教授 ： 楊祝壽 ； 李粵堅

大同大學/電機資訊學院/光電工程研究所/碩士(2011年)

摘要

以電漿補助式分子束磊晶系統在藍寶石基板上成長氧化銦鋅磊晶層，利用不同銦的加熱溫度控制氧化銦鋅磊晶層銦的濃度。藉由能量散佈光譜儀來分析，氧化銦鋅磊晶層中銦的濃度為0 ≦ x ≦ 1。我們從X射線繞射儀觀察到，當銦含量大於0.02時，將會發現金屬銦(1 0 1)及(0 0 2)的相出現。而銦的含量增加到0.16時，金屬銦的相消失，同時氧化銦(2 2 2)的相逐漸出現並且和氧化鋅(0 0 2)相共存在一起。在低溫光激螢光光譜觀察到，銦掺雜的量越多，近能隙部分的半高寬逐漸變寬。其螢光訊號是由近能隙和侷限態所提供的，分別往藍移以及紅移。氧化鋅到氧化銦鋅磊晶層中，隨銦濃度增加至0.38時載子濃度從1017上升到1020 cm-3。此外，我們發現共摻雜銅與銦於氧化鋅中，有助於提高螢光效率。
在化學合成氧化鋅奈米柱的部份，前驅物是利用去離子水溶液混合硝酸鋅和六亞甲基四胺，利用微波合成系統。此研究是使用不同比例的硝酸鋅和六亞甲基四胺來控制成長不同型貌的氧化鋅奈米柱。我們利用改變硝酸鋅和六亞甲基四胺的比例來調整氧化鋅奈米柱形貌。從拉曼散射和光激螢光光譜結果表示，顆粒大小和尺寸會影響其光學特性；拉曼光譜中可發現與缺陷有關的縱向光學聲子(576 cm-1)的訊號強度會隨著硝酸鋅比例的增加而減少。而在光激螢光光譜的結果中，發現樣品在近能隙的螢光強度會隨著前趨物比例的增加而增加，證明其缺陷濃度有明顯的降低。

關鍵字

氧化銦鋅 ； 分子束磊晶系統 ； 氧化鋅奈米粉末 ； 微波合成系統

並列摘要

Zn1-xInxO epilayers (0 ≦ x ≦ 1) were grown on sapphire substrate by using plasma-assisted molecular beam epitaxy (PA-MBE). The Indium concentration was controlled by varying the Indium cell temperature. The Indium concentration (x) was determined by energy dispersive spectrometer (EDS). The growth rate of Zn1-xInxO epilayers, which were estimated from the scanning electron microscope (SEM), correlated to the evaporated flux of group III element. In X-ray diffraction results, when the Indium concentration at x = 0.02, the two new phases appear at 33.1 and 36.04 degree. These correspond to the In (1 0 1) and In (0 0 2). When the x = 0.16, the metallic-In phase is suppressed. At the same time, the In2O3 (2 2 2) and ZnO (0 0 2) are co-exist. In the photoluminescence (PL) spectra, the origin of near band edge emission (NBE) of ZnInO is bound excition (BE) and localized state emission (LE). In addition, the photon energy of BE and LE exhibits blue and red-shift with In content increasing, respectively. The carrier concentration of Zn1-xInxO epilayers are varied from 1017 to 1020 cm-3. Furthermore, the luminescence efficiency of ZnInO is enhanced by co-doped Cu.
In the chemical section, we present morphology control investigations on zinc oxide (ZnO) nanorods synthesized by microwave heating of a mixed zinc nitrate hexahydrate and hexamethylenetetramine (HMTA) precursors in deionized water (DI water). XRD and SEM images are utilized to examine the crystalline quality as well as the morphological properties of the ZnO nanorods. It is found that the morphology control can be achieved by simply adjusting the reactant concentrations and the molar ratio of zinc nitrate hexahydrate to HMTA. The Raman scattering and PL spectroscopy measurements were demonstrated to study the size- and shape-dependent optical response of the ZnO nanorods. The Raman scattering result shows that the intensity of longitudinal optical (LO) mode at around 576 cm-1 decreases with the molar ratio of zinc nitrate hexahydrate to HMTA increases, indicating the reduction of defect concentrations in the synthesized ZnO nanorods. Room-temperature PL spectrum of the synthesized ZnO nanorods reveals an ultraviolet (UV) emission peak and a broad visible emission. An enhancement of UV emission appears in the PL spectra as the molar ratio of zinc nitrate hexahydrate to HMTA increases, indicating that the defect concentration of the synthesized ZnO nanorods can be reduced by increasing the molar ratio.

並列關鍵字

Zn1-xInxO ； MBE ； ZnO nano-particals ； Microwave-assisted Synthesis

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