可用來研究電漿子及幫助蝕刻矽晶體的 銀奈米粒子有序陣列

Abstract

我們用四種方法來成長銀奈米粒子: (1) 蒸鍍銀薄膜在矽基板表面, 經由限制性自組織來形成奈米粒子, (2)在氧化鋁孔洞基板, 經由電化學過程來形成奈米粒子, (3)用電子束顯影蝕刻術, 來製造奈米粒子, (4)直流置換矽為銀奈米粒子. 其中方法 ‘1-3’可形成有序銀奈米粒子, 而方法 ‘4’可長出自組的銀奈米粒子, 特別地, 方法 ‘2’可形成間隙小於5奈米之銀粒子雙連體或三連體陣列. 方法 ‘1,2,4’ 的機制將會討論. 我們使用掃描電子穿透顯微術—也就是電子能量損失能譜術, 對方法 ‘1’長出的銀奈米粒子, 進行表面電漿子掃描分析. 實驗的結果與理論的計算相符合. 藉著不同型態的銀奈米結構, 我們可以對矽(100)基板做方向性蝕刻, 也找到這種蝕刻的關鍵參數. 經由高解析電子顯微鏡, 就地觀測的拉曼光譜術, 以及傅利葉轉換紅外線光譜術等觀測, 我們釐清在矽基板進行置換銀電鍍, 以及藉銀粒子輔助的矽晶蝕刻等現象的機制.

Silver nanoparticles have been grown by four different methods viz: (1) constrained self organization of Ag films onto silicon substrates, (2) electrochemical growth of Ag into custom-designed porous anodic alumina templates, (3) electron-beam lithography, and (4) galvanic displacement of Si by Ag. Methods ‘1-3’ yield ordered arrays of Ag nanoparticles whereas method ‘4’ results in growth of self organized Ag nanoparticles. Only method ‘2’ produces arrays of dimers and trimers of silver nanoparticles with sub-5 nm interparticle gap. Mechanisms for growth of Ag nanoparticles by methods ‘1, 2’, and ‘4’ have been discussed. Surface plasmons of Ag nanoparticles formed by method ‘1’ have been mapped by scanning electron transmission microscope (STEM)–electron energy loss spectroscopy (EELS). Experimental results are found to be consistent with STEM-EELS calculations. Directional etching of Si(100) substrates by different types of Ag nanostructure is achieved. Key parameters which promote the directional etching have been identified. Mechanisms of “galvanic displacement mediated Ag plating on Si” and “Ag-assisted etching of Si” are elucidated by high resolution electron microscopy and in-situ Raman and FTIR spectroscopy.