近年來電漿子學受到關注，開啟了金屬在奈米尺度下進行光學研究的篇章，可藉由改變金屬的奈米結構形狀、結構大小、週期性排列方式等來操控其光性變化，而對奈米金屬進行氧化亦能改變其光學性質，故本篇論文是在磷酸中來對鎵奈米顆粒進行電化學氧化，透過施加不同定電壓值及定電流值，並持續不同時間，氧化後並量測其光學性質之變化。結果顯示隨施加定電壓的時間增加，光譜特徵峰紅位移的量也隨之增加，但特徵峰也會逐漸寬化而變得不明顯，而施加的電壓值大小亦影響了最大可紅位移量及得到最大紅移量所需時間：給予的定電壓值愈大，特徵峰之最大紅移量愈少，所需時間愈短；電壓小則反之。鎵奈米粒子在經由電化學氧化後，其形貌會有凹陷變形，文獻中表明氧化鎵的增厚對電漿子共振之紅位移量貢獻有限，本研究亦透過高溫熱氧化法使鎵奈米粒子氧化，其光譜紅移量亦相當有限，故推測電化學氧化造成的紅位移多是來自變形的貢獻。經由電化學氧化法已可調控鎵奈米粒子電漿子共振的紅位移量，為求能調控特徵峰的位移及重複調控，本研究將試片浸泡於氫氧化鈉溶液中以蝕刻掉氧化層，結果顯示蝕刻後鎵奈米粒子粒徑縮小且變回如未氧化前之球形，光譜特徵峰亦藍移，再次施加電壓後依然可再氧化並紅移，且可紅移量依然有接近40~50 nm，故最終可藉電化學氧化搭配氫氧化鈉濕蝕刻法達到調控光譜的目的。

The plasmonic response of metallic nanoparticles to external electromagnetic fields makes them attractive for a wide range of applications. In this study, the effect of the oxidation of gallium nanoparticles (Ga NPs) on their plasmonic properties is investigated. Electrochemical oxidation treatments, varying voltage and time, were carried out in order to increase experimentally the Ga2O3 shell thickness in the NPs.
In the result, a clear redshift of the peak wavelength is observed, and the gallium nanoparticles would deform. The less redshift by applying the higher voltage and vice versa. Several research implied that oxidation makes slight red-shift, we consider that the deformation is the main reason to cause large redshift. In order to make the spectrum tunable, we try to etch the gallium oxide layer after electrochemical oxidation by dipping in NaOH solution and it can make the spectrum blue-shift. The dissertation successfully figure out a method to make the spectrum of gallium nanoparticles tunable.

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