烷硫醇分子在矽(111)面上之自組裝特性研究

Formation and Characterization of Alkanethiol Self-Assembled Monolayers on Si (111) Surface

婁介嶺(Jie-Ling Lou)

指導教授 ： 蘇雲良 ； 陳家浩

國立清華大學/原子科學院/先進光源科技學位學程/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00265

摘要

此篇論文探討藉由UV光催化硫烷類分子成長於氫化矽表面上之特性研究。實驗中選用1－十二硫醇(1-dodecanethiol，DDT)分子為研究基礎，進而成長良好的DDT/Si(111)薄膜。再透過水滴接觸角量測、高解析X光光電子能譜儀(HRXPS)、X光微結構吸收光譜(NEXAFS)、衰減式全反射紅外光吸收光譜技術的解析(ATR-FTIR)，將對於DDT/Si(111)薄膜的表面濕潤特性、電子結構、分子排列、分子間偶極矩振動模式等，加以透徹分析與討論。
實驗結果顯示，成長DDT/Si(111)薄膜呈現疏水性的101度，藉由HRXPS偵測薄膜表面碳1s、硫2p、矽2p、氧1s電子結構訊號，均反應出DDT分子以S－Si鍵結為成長基礎，並在無氧化層的影響下良好成長於氫化矽基材表面上。另外，由NEXAFS和ATR-FTIR解析DDT分子碳鍵為有序結構排列且站立角約56度，進而推估薄膜層厚度約15Å。綜合以上多方面的數據，都逐一顯示該參數成長之下，可成功製備良好的DDT/Si(111)薄膜。
進一步探討DDT/Si(111)薄膜對於大氣環境的抵抗能力。從HRXPS分析矽2p與硫2p能譜顯示薄膜在大氣中存放一週後逐漸開始氧化，再利用KOH溶液清洗DDT/Si(111)薄膜，將驗證大氣使表面原有的破洞或殘缺、以及分子自然排列domain boundary之部分開始氧化。另一方面，又藉此分析氧含量的多寡，透過計算得到DDT覆蓋表面比例高達到約93%。總結以上各種的量測與試驗，確認成功的製備出以S－Si鍵結作為基礎成長的單分子層系統，對於能在乾淨除氧的矽基材上之應用更加推廣及發展。

關鍵字

自組裝分子膜 ； 氫化矽(111)表面 ； 1-十二烷硫醇分子 ； 有機薄膜 ； 烷基硫醇

並列摘要

In this thesis, we have studied the formation of 1-dodecanethiol (DDT) self-assembled monolayers (SAMs) grown on hydrogen-terminated Si(111) surfaces. The surface wettability, electronic properties, molecular orientation, and molecular oriented transition dipole moment of the DDT/Si(111) film were studied by water contact angle, high-resolution X-ray photoelectron spectroscopy (HRXPS), polarized near-edge X-ray absorption fine structure (NEXAFS), and attenuated total reflection fourier transform infrared(ATR-FTIR).
The 101° water contact angle and HRXPS measurement indicate the DDT is almost fully covered on Si forming a high quality and densely peacked methyl-terminates surface. Furthermore, a combination of NEXAFS and ATR-FTIR measurements revealed a structure of ordered alkyl chains tilted 33.4° related to the surface normal and calculated film thickness of 15 Å.
To investigate the durability of the monolayer, the fresh DDT/Si(111) samples were kept in atmospheric condition from one day up to a month. From Si 2p and S 2p spectra, a slight increase of the oxide component was observed after a week. Moreover, by immersing sample into potassium hydroxide solution, we concluded that the oxidation of DDT/Si(111) is starting from the defect sites and domain boundary of the SAMs.

並列關鍵字

Self-assembled monolayers (SAMs) ； Hydrogen-terminated Si(111) surfaces ； 1-dodecanethiol (DDT) ； Organic thin film ； Alkanethiolate

參考文獻

[1.1] J. M. Buriak, Chem. Rev., 2002, 102, 1272.

[1.3] A. C. Templeton et al., Acc. Chem. Res., 2000, 33, 27.

[1.4] J. C. Love et al., Chem. Rev., 2005, 105, 1103.

[1.5] G. M. Whitesides and Y. Xia, Angew. Chem. Int. Ed., 1998, 37, 550.

[2.1] W. C. Bigelow et al., J. Colloid Interface Sci., 1946, 1, 513.