矽化鐵奈米結構的成長與特性研究

Synthesis and Properties of the Iron Silicide Nanostructures

洪世瑋(Shih-Wei Hung)

指導教授 ： 陳力俊

國立清華大學/工學院/材料科學工程學系/博士(2011年)

摘要

一維過渡金屬矽化物的奈米結構在電子以及光電元件的應用當中，由於許多物理特性優於傳統的塊狀材料，引起了科學界相當廣泛的研究興趣。本研究中，合成出自催化生長的鐵-矽奈米線，並針對其結構以及光、電、磁物理特性探討分析。
其中，利用一自發性的化學反應方法來合成鐵-矽奈米線，亦針對可能的生長機制以及影響奈米線生長的變因做討論。所合成出的β-FeSi2在物理性質方面的表現，除了在室溫下放出波長為1.5 m的紅外光外，也觀察到室溫鐵磁性以及高磁阻變化的特性。這些性質皆顯示此材料在自旋電子的奈米元件中其潛在的應用性。
在另一方面，也合成出FeSi 的奈米線。除了發現其溫鐵磁性外，也將FeSi 奈米線應用在記憶體元件當中。元件的記憶體效應來自於在SiO2 中引入FeSi奈米線能提升記憶體元件捕獲電子電動的能力。此行為顯示了FeSi奈米線在非揮發性記憶體元件的應用價值。

關鍵字

矽化鐵奈米線, 發光, 室溫鐵磁性, 磁阻

並列摘要

One dimensional transition metal silicide nanostructures have attracted much attention for their potential applications in electronic and optoelectronics nanodevices as well as for their intriguing physical properties different from those of bulk materials. In the present research, we report the growth and structural characterization of the self-catalyzed iron silicide nanowires. In addition, the specific optical, electrical and magnetic properties of the nanowires were also investigated.
A spontaneous chemical reaction method was used for the fabrication of the iron silicide nanowires. The possible growth mechanism and the variables that affect the nanowire growth were also discussed. The as-synthesized β-FeSi2 nanowires exhibit photoluminescence at a wavelength of 1.54 μm, which is suitable for the Si-based optical communication, at room temperature. In addition, the room temperature ferromagnetism and high magnetoresistance performance indicates that β-FeSi2 nanowires are potentially applicable for spintronic nanodevices.
On the other hand, the room-temperature ferromagnetism of the as-grown FeSi nanowires compared to that of bulk FeSi at 4 K was found. The fabricated memory devices based on FeSi nanowires showed significant C-V hysteresis, exhibiting the memory effect. The strong memory effect can be accounted for by the presence of defects or dangling bonds on the surface of the FeSi nanowires embedded in SiO2 layer, which enhances the trapping density for non-volatile memory applications.

並列關鍵字

iron silicide nanowires, luminescence, room temperature ferromagnetism, magnetoresistance

參考文獻

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