超高真空原子尺度Au_(x)/Si(111)-(7×7)表面吸附的电荷分布测量  

Measurement of distribution of charge adsorbed on Aux/Si(111)-7×7 surface on an atomic scale in ultra-high vacuum

作　　者：冯婕 郭强[1,2,3] 舒鹏丽 温阳 温焕飞 马宗敏[1,2,3] 李艳君 刘俊[1,2,3] 伊戈尔·弗拉基米罗维奇·雅明斯基 Feng Jie;Guo Qiang;Shu Peng-Li;Wen Yang;Wen Huan-Fei;Ma Zong-Min;Li Yan-Jun;Liu Jun;Igor Vladimirovich Yaminsky(State Key Laboratory of Dynamic Measurement Technology,North University of China,Taiyuan 030051,China;School of Instrument and Electronics,North University of China,Taiyuan 030051,China;Shanxi Key Laboratory of Quantum Sensing and Precision Measurement,Taiyuan 030051,China;Department of Applied Physics,Graduate School of Engineering,Osaka University,Osaka 5650871,Japan;Advanced Technologies Center,Moscow State University,Moscow 119311,Russia)

机构地区：[1]中北大学,省部共建动态测试技术国家重点实验室,太原030051 [2]中北大学仪器与电子学院,太原030051 [3]量子传感与精密测量山西省重点实验室,太原030051 [4]日本大阪大学工学研究科精密科学应用物理学,日本大阪5650871 [5]俄罗斯国立莫斯科大学先进技术中心,俄罗斯莫斯科119311

出　　处：《物理学报》2023年第11期165-175,共11页Acta Physica Sinica

基　　金：国家自然科学基金国际合作与交流项目(批准号:62220106012);国家自然科学基金(批准号:51727808,61874100,51922009);山西省杰出青年基金(批准号:202103021221007);山西省“1331”项目重点学科建设基金(批准号:1331KSC)资助的课题.

摘　　要：原子尺度表面吸附Au原子的物理化学性质对研究纳米器件的制备以及表面催化等起着非常重要的作用.利用调频开尔文探针力显微镜研究了室温下Au在Si(111)-(7×7)表面吸附的电荷分布的特性.首先,利用自制超高真空开尔文探针力显微镜成功得到了原子尺度Au在Si(111)-(7×7)不同吸附位的表面形貌与局域接触电势差(LCPD);其次,通过原子间力谱与电势差分析了Au/Si(111)-(7×7)特定原子位置的原子特性,实现了原子识别;并通过结合差分电荷密度计算解释了Au/Si(111)-(7×7)表面间电荷转移与Au的吸附特性.结果显示,Au原子吸附有单原子和团簇形式.其中,Au团簇以6个原子为一组呈六边形结构吸附于Si(111)-(7×7)的层错半单胞内的3个中心原子位;单个Au原子吸附于非层错半单胞的中心顶戴原子位;同时通过电势差测量得知单个Au原子和Au团簇失去电子呈正电特性.表面差分电荷密度结果显示金在吸附过程中发生电荷转移,失去部分电荷,使得吸附原子位置上的功函数局部减少.在短程力、局域接触势能差和差分电荷密度发生变化的距离范围内,获得了理论和实验之间的合理一致性.The physicochemical properties of Au atoms adsorbed on the surface on an atomic scale play a very important role in preparing nanodevices and surface catalysis.In this paper,we use frequency modulated Kelvin probe force microscopy(FM-KPFM)to study the multi-bit adsorbed charge distribution of Au on the surface of Si(111)-(7×7)at room temperature.Firstly,the surface topography and local contact potential difference(LCPD)of Au at different adsorption sites in Si(111)-(7×7)are successfully obtained by using home-made ultra-high vacuum Kelvin probe force microscopy.Secondly,we analyze the atomic characteristics of specific atomic positions of Au/Si(111)-(7×7)by force spectroscopy and potential difference,and realize the atomic identification.The adsorption characteristics of Au/Si(111)-(7×7)surface charge transfer and Au are explained by combining differential charge density calculations.The results show that Au atom adsorption mainly is in the form of single atom and cluster.Specifically,the Au cluster is adsorbed at the three central positions of Si(111)-(7×7)in a hexagonal structure of six atoms.Individual Au atoms are adsorbed to the positions of central adatoms of Si(111)-(7×7).At the same time,through the measurement of potential difference,it is known that a single Au atom and Au cluster lose electrons,presenting a positive electrical characteristic.The results of surface differential charge density show that Au undergoes charge transfer during adsorption,losing part of the charge,which locally reduces the work function at the position of the adsorbed atom.In the range of distances where short-range forces,local contact potential energy differences and differential charge densities change,the theoretical results and experimental results are in reasonable agreement.

关 键 词：开尔文探针力显微镜 Si(111)-(7×7) 局域接触势能差 表面电荷 

分 类 号：O641.1[理学—物理化学] O647.3[理学—化学]