Si(111)-7×7表面上C_(60)多层膜的生长及其纳米摩擦学性质  

Growth and Nanotribological Properties of C_(60) Multilayer Films on Si(111)-7×7 Surface

作　　者：杜晓清[1,2] 李慧琴[2] 朱齐荣[2] 邹志强[2] 梁齐[1,2] 

机构地区：[1]上海交通大学物理系,上海200240 [2]上海交通大学分析测试中心,上海200240

出　　处：《物理化学学报》2011年第10期2457-2461,共5页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(10974134)资助项目~~

摘　　要：在超高真空(UHV)条件下,用分子束外延(MBE)方法,通过对生长过程中蒸发速率和衬底温度等参数的控制,可以避免C_(60)分子在Si(111)-7×7重构表面多层生长时团聚岛的形成,得到了逐层生长的C_(60)多层膜.同时利用超高真空扫描隧道显微镜(UHV-STM)对这种多层膜结构进行了观察并对这种规象产生的机理做了分析.测定了不同层数C_(60)薄膜的黏附力和摩擦力曲线,发现分子层数对薄膜的摩擦性质有显著影响,随着沉积层数的增加,样品的摩擦力明显降低,摩擦系数也有降低的趋势.由于分子层数的增加导致C_(60)分子转动程度增强,本文得出结论,摩擦力的降低是由C_(60)分子的转动引起的,C_(60)分子在这里充当了"纳米滚动轴承",即C_(60)分子的转动为微观结构提供了能量耗散通道.C60 layer by layer films without clusters were obtained on Si（111）-7 ×7 reconstructed surface by controlling parameters such as the evaporation speed and the temperature of substrate during the growth process. The experiments were carried out under ultra-high vacuum （UHV） using molecular beam epitaxy （MBE）. These films were observed by ultra-high vacuum scanning tunneling microscopy （UHV-STM） and the mechanism of this phenomenon was analyzed. The adhesion and frictional force curves of these C60 films with different layers were measured. Their frictional properties were found to be affected by the number of layers. The frictional force decreased obviously with the increase in layers and the frictional coefficient also showed a downward tendency. Our simulation showed that adhesion was not the main effect that led to a decrease in the frictional force. Since the increase of layers leads to a higher level of rotation for C60 molecules, we conclude that the decrease in the frictional force is caused by the rotation of the C60 molecules. C6o molecule acts as ＂nano rolling bearing＂ here. That is, the rotation of the C60 molecules provides a channel for energy dissipation in the microstructure. These kinds of multilayer films make it possible for us to study the relationship between the rotation of C60 molecule and its other properties.

关 键 词：富勒烯: 分子束外延: 薄膜生长: 纳米摩擦性质:扫描隧道显微镜 

分 类 号：O613.7[理学—无机化学]