Hoque E, Derose J A, Hoffmann P, Mathieu H J, Bhushan B, Cichomski M
LMCH, IMX, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
J Chem Phys. 2006 May 7;124(17):174710. doi: 10.1063/1.2186311.
Substrates of aluminum (Al) deposited by physical vapor deposition onto Si substrates and then chemically reacted with perfluorodecylphosphonic acid (PFDPAlSi), decylphosphonic acid (DPAlSi), and octadecylphosphonic acid (ODPAlSi) were studied by x-ray photoelectron spectroscopy (XPS), contact angle measurements, atomic force microscopy (AFM), and friction force microscopy, a derivative of AFM, to characterize their surface chemical composition, roughness, and micro-/nanotribological properties. XPS analysis confirmed the presence of perfluorinated and nonperfluorinated alkylphosphonate molecules on the PFDPAlSi, DPAlSi, and ODPAlSi. The sessile drop static contact angle of pure water on PFDPAlSi was typically more than 130 degrees and on DPAlSi and ODPAlSi typically more than 125 degrees indicating that all phosphonic acid reacted AlSi samples were very hydrophobic. The surface roughness for PFDPAlSi, DPAlSi, ODPAlSi, and bare AlSi was approximately 35 nm as determined by AFM. The surface energy for PFDPAlSi was determined to be approximately 11 mNm by the Zisman plot method compared to 21 and 20 mNm for DPAlSi and ODPAlSi, respectively. Tribology involves the measure of lateral forces due to friction and adhesion between two surfaces. Friction, adhesion, and wear play important roles in the performance of micro-/nanoelectromechanical systems. PFDPAlSi gave the lowest adhesion and coefficient of friction values while bare AlSi gave the highest. The adhesion and coefficient of friction values for DPAlSi and ODPAlSi were comparable.
通过物理气相沉积将铝（Al）沉积在硅（Si）衬底上，然后使其与全氟癸基膦酸（PFDPAlSi）、癸基膦酸（DPAlSi）和十八烷基膦酸（ODPAlSi）发生化学反应，通过X射线光电子能谱（XPS）、接触角测量、原子力显微镜（AFM）以及AFM的衍生技术摩擦力显微镜对所得衬底进行研究，以表征其表面化学成分、粗糙度以及微/纳米摩擦学特性。XPS分析证实了PFDPAlSi、DPAlSi和ODPAlSi上存在全氟和非全氟烷基膦酸酯分子。纯水在PFDPAlSi上的静置滴静态接触角通常大于130度，在DPAlSi和ODPAlSi上通常大于125度，这表明所有膦酸反应后的AlSi样品都具有很强的疏水性。通过AFM测定，PFDPAlSi、DPAlSi、ODPAlSi和裸AlSi的表面粗糙度约为35纳米。通过Zisman图法测定，PFDPAlSi的表面能约为11 mN/m，而DPAlSi和ODPAlSi的表面能分别为21 mN/m和20 mN/m。摩擦学涉及测量两个表面之间由于摩擦和粘附产生的横向力。摩擦、粘附和磨损在微/纳机电系统的性能中起着重要作用。PFDPAlSi的粘附力和摩擦系数值最低，而裸AlSi的最高。DPAlSi和ODPAlSi的粘附力和摩擦系数值相当。
