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標題: | 一維氮化鎵奈米線摻雜鈷稀磁性半導體之製備與研究 Fabrication and diluted magnetic property of (Ga,Co)N nanowires |
作者: | Yu-Lun Liu 劉宇倫 |
指導教授: | 馮哲川(Zhe-Chuan Feng) |
關鍵字: | 氮化鎵,奈米線,稀磁性半導體, gallium nitride,nanowires,diluted magnetic semiconductor, |
出版年 : | 2007 |
學位: | 碩士 |
摘要: | 奈米線、奈米尖錐、奈米帶等一維奈米結構因具有獨特的光性、電性和機械性質而成為現今的熱門研究領域。一維奈米材料在過去的研究往往集中在其特殊的光學性質以及電學性質上,鮮少有關於磁性方面的深入研究。我的研究將著重於一維氮化鎵奈米線在摻雜鈷元素之後的結構影響以及其磁性性質。目前半導體的研究已經進入了奈米級的進展,我們在這微小的世界中必須開始考慮載子的自旋及其傳導的影響,稀磁性半導體的研究吸引了許多相關研究人員的重視,而將其視為未來結合電學及磁學的關鍵材料。再者一維奈米結構也具備元件的功能,所以這種一維奈米結構可以作為自旋電子學及奈米積體電路中基礎元件的應用。
在2000年T. Dietl 等人利用理論的模擬計算和實驗的對照,發現在砷化鎵參雜錳元素的吻合,並推導其他相關的半導體材料在其磁性方面的特性。發現在氮化鎵材料上具有室溫鐵磁性的性質,被預期能運用在磁性記憶體的元件和積體電路的材料上。本實驗利用常壓環境下以及高溫爐式製程的APCVD,成功地在矽基板上成長氮化鎵奈米線材料,並經由離子佈植的方式來摻雜磁性原子,最後在利用高溫爐作熱退火的實驗。利用掃描式電子顯微鏡、X光繞射譜線、高解像能穿透式電子顯微鏡、及X光能量散佈光譜儀可測定出所成長之氮化鈷鎵奈米線為高度方向性的單晶奈米結構。本研究中,從掃描式電子顯微鏡觀察到樣品在經過離子佈植之後有明顯的彎曲及表面破壞現象。而在X光繞射譜線發現無第二相化合物的形成,且晶格結構上有明顯被擴張和扭曲的現象,研判是由於在經過離子佈植後產生的應力所造成,而此現象在經過熱退火的實驗後有明顯的改善。高解像能穿透式電子顯微鏡以及X光能量散佈光譜儀分析出離子佈植過後奈米線內無明顯的叢聚及第二相現象和在奈米線表面上的成份分析。最後以超導量子干涉儀量測試片的磁性質,利超導量子干涉儀系統在300K測量時,得到了一個明顯的磁滯曲線圖,推測樣品在室溫時有鐵磁性的行為。 Nanowires, nanotips, and nanobelts, became hot research field with uniqueness optical, electrical and mechanical properties recently. 1D nanostructure had attracted much attention on their special optical and electrical properties in the past, but there only seldom investigation mentions about magnetic behavior. My investigation will focus on cobalt doped gallium nitride nanowires with their structure influencing and magnetic nature. The research of semiconductor has already entered the process in nano scale, and we must begin to consider the carriers’ spin and their conductive properties in this small world. The investigation of diluted magnetic semiconductors has attracted the attention of a lot of relevant researchers, and was regarded as the key material combining electricity and magnetism in the future. Moreover one dimensional structure possesses functions of devices too, so one dimensional nanostructure can be efficiently applied in Spintronics and integrated circuit system. In 2000, T. Dietl utilized theoretical simulation to be contrasted with the experimental, and he found the manganese doped gallium arsenide were identical, and derive other magnetic characteristics in its relevant semiconductor materials. In this study, gallium nitride nanowires were successfully grown on Silicon substrate using a simple resistive heated furnace, APCVD system, at room temperature. Then we used tandem accelerator to implant magnetic atoms. Finally, the sample will be annealed by the furnace for defect removing. From scanning electron microscopy (SEM), x-ray diffraction (XRD) spectra, high resolution electron microscope (HRTEM) measurement and energy dispersive X-ray spectroscopy (EDS), analysis revealed that single crystalline of cobalt doped gallium nitride nanowires. The scanning electron microscope (SEM) investigations on the gallium nitride (GaN) nanowires show a surface morphology, and we can clearly see the wires bended and surface damaged. X-ray diffraction (XRD) spectra show no secondary phase formation after ion implantation, and the lattice was extended and short ranged distorted. This phenomenon was predicted by stress in the nanowires. After thermal annealing, the structure shows recrystallization clearly in the XRD spectra. High resolution electron microscope (HRTEM) measurement and energy dispersive X-ray spectroscopy (EDS) show no clusters obviously and atomic analysis on the surface. Finally, we used superconducting quantum interference device (SQUID) for magnetic measurement, and saw a hysteretic curve at 300K. The result shows the cobalt doped gallium nitride nanowires with room temperature ferromagnetic properties. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/25372 |
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