Fréchette Joëlle, Maboudian Roya, Carraro Carlo
Department of Chemical Engineering, University of California, Berkeley, California 94720, USA.
Langmuir. 2006 Mar 14;22(6):2726-30. doi: 10.1021/la053241z.
The thermal stability of perfluoralkylsiloxane monolayers in a vacuum is investigated via X-ray photoelectron spectroscopy (XPS) for temperatures up to 600 degrees C. 1H,1H,2H,2H,-perfluorodecyltrichlorosilane (FDTS) monolayers are deposited on oxidized Si(100) surfaces from the vapor phase with various degrees of surface coverage. Significant monolayer desorption is observed to occur at temperatures below 300 degrees C regardless of the initial monolayer coverage. The desorption mechanism follows first-order kinetics and is independent of the initial coverage. Removal of FDTS is found to occur by the loss of the entire molecular chain, as evidenced by the fact that the CF(3)/CF(2) peak area ratios remain unaffected by the annealing process although CF(n)()/Si peak ratio declines with annealing. This is in sharp contrast to the behavior observed for octadecyltrichlorosilane monolayer for which elevated temperature leads to C-C bond breakage and successive shortening of the alkyl chain. It is also shown that the binding energy and the shape of the F 1s line are good indicators of the degree of disorder in the chain, as well as a measure of the interaction of the chain with the silicon surface.
通过X射线光电子能谱（XPS）研究了全氟烷基硅氧烷单层膜在真空中至600摄氏度的热稳定性。1H，1H，2H，2H-全氟癸基三氯硅烷（FDTS）单层膜从气相沉积在具有不同表面覆盖率的氧化Si（100）表面上。无论初始单层覆盖率如何，在低于300摄氏度的温度下都观察到明显的单层解吸。解吸机制遵循一级动力学，且与初始覆盖率无关。发现FDTS的去除是通过整个分子链的损失发生的，这由以下事实证明：尽管CF（n）/Si峰比随退火而下降，但CF（3）/CF（2）峰面积比不受退火过程影响。这与十八烷基三氯硅烷单层膜的行为形成鲜明对比，对于后者，升高温度会导致C-C键断裂和烷基链的连续缩短。还表明，F 1s线的结合能和形状是链中无序程度的良好指标，也是链与硅表面相互作用的一种度量。
