氧化鋅鈷摻鋁薄膜的高頻磁電特性

High Frequency Magnetic-electrical Properties of Al-dopped Zn1-xCoxO Thin Films

徐兆逸(Chao-Yi Hsu)

指導教授 ： 傅昭銘

國立臺灣大學/理學院/物理研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.10717

摘要

稀磁性半導體(Diluted magnetic semiconductors)結合半導體與磁性材料的特性，預期可作為自旋電子元件應用。過渡金屬摻雜氧化鋅具有磁-光-電偶聯之物理特性，成為熱門研究稀磁性半導體材料系統。本研究探討鋁摻雜氧化鋅鈷（Zn1-X-YAlXCoYO）稀磁性半導體薄膜之高頻阻抗特性，並藉阻抗頻譜分析以探討鋁摻雜濃度對樣品磁電特性的影響。實驗上使用高頻阻抗量測儀量測鋁摻雜氧化鋅鈷薄膜的阻抗頻譜特性，並經由介電遲豫理論和古典電磁理論分析樣品的交變電磁動力學行為。
由阻抗頻譜所量測的結果顯示，阻抗頻譜特性具有磁介電體(如鑭鍶錳氧化物、鎳鋅鐵氧化物等)行為，且鋁摻雜濃度會系統化影響阻抗頻譜響應特性。為探討磁電頻率響應機制，乃先以Cole-Cole理論模型來分析實驗所得之阻抗頻譜，分析結果揭示阻抗頻譜係有多重遲豫反應貢獻。再以古典電磁理論，並考慮磁後效應與介電弛豫機制，進一步對阻抗頻譜擬合分析，分析結果表示，摻鋁氧化鋅鈷薄膜之高頻電磁行為乃由微觀磁元與介電動力學機制所貢獻。本研究結果將可提供作為日後自旋電子元件應用製作之参考。

關鍵字

稀磁性半導體 ； 氧化鋅鈷薄膜 ； 高頻阻抗 ； 阻抗頻譜

並列摘要

Diluted magnetic semiconductor (DMS) is technological interest for applications of interdisciplinary materials science due to the charge and spin degrees freedom accommodated into single matter resulting in interesting magneto-optical, magnetoelectronic, and other properties. Especially, zinc oxides partially (< 10 at.%) substituting of transition metal (TM) ions has attracted much attention recently because of its potential applications in the spintronic and optoelectronic devices such as transparent conductive electrodes.
In this work, impedance spectroscopy method has been applied to characterize the Al doping effects on the electric and magnetic properties of ZnCoO thin films. The relaxation contribution from different structural origin such as grains and grain boundary has been carry out by employing the Cole impedance model. Moreover, the electromagnetic transport properties also been analyzed based on the classical electromagnetism, which taking into account the occurrence of dielectric relaxation and magnetic-after effect when the samples were subjected to alternating electromagnetic field. Further theoretical investigations of the fitting parameters suggest that the Zn1-X-YAlXCoYO may applicable to high frequency electro-magnetic devices.

並列關鍵字

DMS ； ZnCoO:Al thin film ； high frequency Impedance ； Impedance spectrum

參考文獻

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