Vapor-deposition of aluminum on thiophene-terminated self-assembled monolayers on gold
Vapor-deposition of aluminum on thiophene-terminated self-assembled monolayers on gold
复制标题
金上噻吩封端的自组装单分子层上铝的气相沉积
DOI：
10.1021/jp030096u
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
J. Whitten
中科院分区：
文献类型：
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作者：
Heejoon Ahn;J. Whitten
用X射线光电子能谱（XPS）和紫外光电子能谱（UPS）研究了12-（3-噻吩基）十二烷硫醇（一种噻吩封端的烷硫醇）在金表面自组装膜上的热沉积过程，并与在1-十三烷硫醇上的热沉积过程进行了比较. C Is和Au 4f峰的强度变化作为铝覆盖率的函数表明热沉积的铝在噻吩封端的自组装单层（SAM）的顶部上形成覆盖层。界面铝与噻吩官能团的强相互作用是由金属诱导的，低结合能的C 1 s光谱中的组件的外观证明。在10°起飞角下进行的XPS测量，其中表面灵敏度增强，显示金属诱导的噻吩S 2 p峰的1.6 eV的位移至较低的结合能。这些表明电子从铝转移到噻吩环。最初沉积的铝在Al 2s光谱中在119.4 eV的结合能处表现出非金属特征，但进一步的铝沉积导致噻吩封端的SAM顶部上的金属覆盖层。UPS测量还表明，铝覆盖噻吩封端的自组装膜，如通过4.4 × 10 - 15原子/cm-2的Al覆盖率完全不存在噻吩的光谱特性所证明的。功函数测量表明，最初沉积的铝生长为电隔离岛，直到超过这个覆盖范围。这种行为是显着不同的1-tridecanethernet上，最初沉积的铝相互作用较弱的烷基ethernet和扩散下的单层的金表面。在噻吩封端的SAM的情况下，渗透的缺乏可能是由于有机表面上的铝原子的流动性较低，与甲基封端的SAM相比，以及它们不能扩散到缺陷部位并渗透通过单层。
Thermal deposition of aluminum in ultrahigh vacuum on a monolayer of 12-(3-thienyl)dodecanethiol, a thiophene-terminated alkanethiol, self-assembled on gold has been investigated by X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS) and compared to aluminum deposition on a monolayer of 1-tridecanethiol. Intensity variations of the C Is and Au 4f peaks as a function of aluminum coverage demonstrate that thermally deposited aluminum forms an overlayer on top of the thiophene-terminated self-assembled monolayer (SAM). Strong interaction of interfacial aluminum with the thiophene functional group is evidenced by the appearance of a metal-induced, low-binding-energy component in the C 1s spectrum. XPS measurements performed at a 10° takeoff angle, where surface sensitivity is enhanced, show a metal-induced shift in the thiophene S 2p peak of 1.6 eV to lower binding energy. These are indicative of electron transfer from aluminum to the thiophene rings. Initially deposited aluminum exhibits a nonmetallic feature in the Al 2s spectrum at a binding energy of 119.4 eV, but further aluminum deposition leads to metallic overlayers on top of the thiophene-terminated SAM. UPS measurements also demonstrate that aluminum covers the thiophene-terminated SAMs, as evidenced by the complete absence of the spectral characteristics of thiophene by an Al coverage of 4.4 x 10 1 5 atoms/cm 2 . Work function measurements suggest that initially deposited aluminum grows as electrically isolated islands until this coverage is exceeded. This behavior is dramatically different from that of 1-tridecanethiol on which initially deposited aluminum interacts weakly with the alkanethiol and diffuses beneath the monolayer to the gold surface. The lack of penetration in the case of the thiophene-terminated SAM probably results from lower mobility of aluminum atoms on the organic surface, compared to methyl-terminated SAMs, and their inability to diffuse to defect sites and penetrate through the monolayer.