Surface chemical conversion of organosilane self-assembled monolayers with active oxygen species generated by vacuum ultraviolet irradiation of atmospheric oxygen molecules
Surface chemical conversion of organosilane self-assembled monolayers with active oxygen species generated by vacuum ultraviolet irradiation of atmospheric oxygen molecules
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DOI：
10.1143/jjap.47.307
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发表时间：
2008-01-01
影响因子：
1.5
通讯作者：
Sugimura, Hiroyuki
中科院分区：
文献类型：
--
作者：
Kim, Young-Jong;Lee, Kyung-Hwang;Sugimura, Hiroyuki
基于水接触角测量、椭圆光度法、X射线光电子能谱和原子力显微镜，研究了利用波长为172 nm的真空紫外（VUV）光照射下的大气氧分子产生的活性氧物种，对氧化物覆盖的硅基板上的正十八烷基三甲氧基硅烷自组装单分子层（ODS-SAM）的顶面进行化学转化。采用化学气相沉积法制备了平均水接触角为104度的ODS-SAM，基底和蒸气温度为150℃。ODS-SAM样品的VUV处理是将样品置于空气中，然后用Xe准分子灯照射样品表面。调节灯和样品之间的距离，使得从灯发出的VUV光在到达样品表面之前几乎完全被大气氧分子吸收，产生活性氧物质，例如臭氧和原子氧。因此，ODS-SAM的表面化学转化主要是通过与活性氧的化学反应来促进的。发现 ODS-SAM 中的光化学变化是表面上极性官能团（例如 -COOH、-CHO 和 -OH）的生成以及随后单层的蚀刻。对辐照参数（例如辐照时间）进行了优化，以实现 SAM 顶面更好的功能化，同时最大限度地减少 ODS-SAM 的蚀刻深度。通过烷基硅烷双层的形成，证明了将另一个 SAM 接枝到带有极性官能团的改性 ODS-SAM 上的能力。
The chemical conversion of the top surface of n-octadecyltrimethoxy silane self-assembled monolayers (ODS-SAMs) on oxide-covered Si substrates using active oxygen species generated from atmospheric oxygen molecules irradiated with vacuum ultraviolet (VUV) light at 172 nm in wavelength has been studied on the basis of water contact angle measurements, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. An ODS-SAM whose water contact angle was 104 degrees on average was prepared using chemical vapor deposition with substrate and vapor temperatures of 150 degrees C. The VUV treatment of an ODS-SAM sample was carried out by placing the sample in air and then irradiating the sample surface with a Xe-excimer lamp. The distance between the lamp and the sample was regulated so that the VUV light emitted from the lamp was almost entirely absorbed by atmospheric oxygen molecules to generate active oxygen species, such as ozone and atomic oxygen before reaching the sample surface. Hence, the surface chemical conversion of the ODS-SAM was primarily promoted through chemical reactions with the active oxygen species. Photochemical changes in the ODS-SAM were found to be the generation of polar functional groups, such as -COOH, -CHO, and -OH, on the surface and the subsequent etching of the monolayer. Irradiation parameters, such as irradiation time, were optimized to achieve a better functionalization of the SAM top surface while minimizing the etching depth of the ODS-SAM. The ability to graft another SAM onto the modified ODS-SAM bearing polar functional groups was demonstrated by the formation of alkylsilane bilayers.