陽極氧化鋁模板輔助生長奈米柱陣列磁性質研究

Magnetic Properties of Electroless-Plated Nanorod arrays Fabricated by Anodic Aluminum Oxide Template

王魏鴻(Wei-Hung Wang)

指導教授 ： 曾院介

國立交通大學/工學院/材料科學與工程系所/碩士(2012年)

https://doi.org/10.6842/NCTU.2012.00762

摘要

本研究以不同陽極氧化處理條件在矽基板上有效控制陽極氧化鋁形
貌，並成功在矽基板上製作出大孔徑的AAO模板。利用無電鍍鎳磷反
應，在矽基板上生長不同孔徑的奈米柱陣列以及薄膜。透過掃描式電
子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)觀察試片之表面形貌以及微
觀結構；使用能量散佈分析儀(EDS)探討化學成分之變化，震動樣品
磁量測儀(VSM)則用來比較各試片的微結構以及磁學特性。我們發現
無電鍍鎳磷為2-3nm鎳奈米晶的超順磁結構，而透過快速退火處理可
以誘發晶粒沿長軸成長提升飽和磁化率以及矯頑磁場，產生超順磁-
鐵磁相轉換；增加退火時間會致使晶粒成長，故造成不同條件之試片
有相異磁性質，暗示磁性的改變是由更微觀的結構改變所驅動。經由
XMCD與sum rule計算出微觀磁矩的磁性貢獻程度(spin moment、
orbital moment)發現無電鍍鎳磷的鐵磁性主要來源為自旋磁矩
(spin moment)的貢獻，而經退火處理後自旋磁矩提升亦可驗證增加
退火時間的確可以提升鐵磁性。

關鍵字

陽極氧化鋁 ； 無電鍍沉積 ； 奈米陣列

並列摘要

In this study, we demonstrate a successful control of the morphology and
pore size of anodic aluminum oxide (AAO) template on silicon substrates with
proper anodizing conditions. These AAO templates enabled the fabrications of
electroless-deposited Ni thin films, and Ni nano-arrays with tunable diameter.
Samples’ surface morphologies were probed using a scanning electron
microscope (SEM, JSM 6500F) operated at 15 kV. A high resolution
transmission electron microscope (HRTEM, JEM-2100F, operated at 200 keV)
was used to probe the atomic-scale images. Compositions were identified by an
energy-dispersive x-ray spectrometry (EDX). Magnetic properties were
analyzed by a vibrating sample magnetometer (VersaLab, quantum design
manufacture). XAS spectra were collected over Ni L2 and L3 edges with a total
electron yield mode (TEY) at BL11A of National Synchrotron Radiation
Research Center (NSRRC). XMCD signals were collected along with XAS by
reversing the x-ray helicity to probe the spin-polarization state of the arrays.
XMCD signals were taken under an applied field of 1 Tesla.
The results show that the magnetic properties were highly dependent on
microstructure and crystallinity. The as-plated sample exhibited a
superparamagnetic behavior and it transformed into ferromagnetic upon
post-annealing process.TEM and VSM results confirmed the grain growth upon
heat treatment, which led to the enhancements of saturation magnetization and
coercivity.
Finally, XMCD sum rules were operated to estimate spin and orbital
moments of the samples. The results show that spin moment dominated the
magnetic properties.

並列關鍵字

anodic aluminum oxide ； electroless deposition ； nanorod-array

參考文獻

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