長碳鏈硫醇於矽111表面自組裝行為之研究

由於矽材料優良的電性與低廉價格，因此廣泛應用於現代人們生活之中，不論是在電子元件、感測器、或是太陽能等領域中，都可以發現其蹤跡。但隨著元件製程日趨減小，矽表面的特性就越顯重要。因此，在本研究中以長碳鏈硫醇對矽半導體表面改質進行研究。我們希望利用自組裝的長碳鏈硫醇單分子薄膜所具有緊密堆積且有序結構特性，以硫醇分子將矽表面完全覆蓋，並且鈍化矽表面活性達到化學與物理特性的穩定。因此，本論文將會深入探討硫醇單分子薄膜的分子結構、成長機制與電子結構等基本性質，以及發展局域表面官能基化的方法，期望未來能夠使硫醇分子應用於實際生活中。我們利用紫外光輔助的方法，將硫醇分子成長在矽(111)的表面上。首先我們在第三章探討紫外光在這反應中所扮演的角色。並在第四章討論硫醇單分子薄膜成長機制與行為。其中藉由操控鏈長長短控制分子間作用大小，其中亦會討論碳鏈奇偶效應對於單分子薄膜的影響。此外，為了使這樣的有機單分子薄膜能能夠實際應用生活之中，我們測試單分子薄膜的熱穩定度，並且進一步了解硫醇分子於矽表面的熱脫附反應行為。另一方面，我們將在第五章討論硫醇單分子膜對矽基板的能帶接合效應，並透過改變矽基板的載子類型與濃度，研究矽的空間電荷層變化情形。發現P型矽表面將會形成反轉的空間電荷層，此一結果將可能有利於應用在太陽能源轉化。最後一部分將會進行局域表面改質的研究，希望藉由這樣的多元官能基的表面，能夠應用於感測元件。其中我們提出兩種方式進行表面局域改質。第一種類型方式是以利用聚焦電子束或X光對有機單分子膜進行特定區域曝射造成破壞分子結構並找出再生長的方法。第二種方式是以氮氣電漿對於表面進行改質，期望能夠利用電漿的高反應性使分子末端改質為與氮相關的官能基。並且透過奈米壓印的方式，使電漿導入通道內造成局域的改質行為。

關鍵字

自組裝分子膜；紫外光光化學反應；硫醇

並列摘要

The silicon is popular using in our practical life, such as electronic devices, sensors, and solar cell, because it performs the well electronic characteristics with the low cost. The modern device size is smaller and smaller causing the surface/volume ration increases a lot. Therefore, the manipulation of Si surface properties attracted many attentions. We propose that the n-alkanethiols molecules serve as the chemical and physic passivation. In this thesis, we discuss the molecular structure, the growth mechanism, and the electronic structure. In addition, we develop two methods for a local functionalization to expect n-alkanethiol/Si for practical applications. We grew n-alkanethiols on bare Si (111) surface by UV-assisted photochemical reaction. First, we discussed the growth mechanism about role of UV irradiation in the photochemical reaction. By controlling the chain length of n-alkanethiols, the growth model is dependent with the intermolecular and molecule-substrate interaction. Further we also found the odd-even effect in the resulting monolayer. To utilize n-alkanethiols/Si in practical applications, we examined its thermal stability with the varied chain length. While the environmental temperature higher than thermally critical temperature, the molecules thermally desorbed from Si surface or embedded into Si substrate. On the other hand, the electronic properties of Si were modified by the implanted n-alkanethiols molecules. We demonstrated the space charge layer of different types and carrier concentration Si surface was changed. The grafted monolayer on p-type Si surface induced an inversion layer which is a potential modification as solar cell applications. In order to promote self-assembled monolayer for more practical application, the local functionalization is required to develop. We utilized two methods: focusing electron or X-ray irradiated to damage the monolayer structure and re-graft the second functionality monolayer. The other method is exposing N2 plasma reacted with the surface functionality to transform the functionality nitrogen related. The plasma radicals drained into the polymeric stamp for the local modification.

並列關鍵字

self-assembled monolayer ； photochemical reaction ； alkanethiols

參考文獻

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長碳鏈硫醇於矽111表面自組裝行為之研究

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