ISSN 0021-3640, JETP Letters, 2010, Vol. 92, No. 7, pp. 449–452. © Pleiades Publishing, Inc., 2010. 449 The continuous shrinking size of Si based devices and associated physical limitations have led to great interest in molecular electronics which is being stud- ied as a successor to conventional Si-based electronics technology. One of its perspectives is the fabrication of devices whose function is governed by single mole- cules so that an important step in single molecule technologies is the linking of individual molecules at specific locations on Si surfaces. Fullerenes are prom- ising candidates for the fabrication of electro-active elements in nano-science applications and can be considered as their building blocks. Therefore, elec- tronics based on individual molecules demands active control of the combined electronic properties of mol- ecule and substrate [1]. An essential peculiarity of fullerenes and their derivatives used in molecular elec- tronics is their ability to trap electrons and to keep holding them for a long time. Fullerenes can also serve as temporal electron acceptors effectively splitting excitons and generating charge carriers-free electrons and holes. Fluorinated fullerenes have been consid- ered as attractive objects for novel material applica- tions due to the possibility of the creation of new wide band gap semiconductors and dielectric materials [2]. In this work we present results of the scanning tunnel- ¶ The article is published in the original. ing microscope (STM) imaging of individual C 60 F 18 molecules deposited on Si(100) – 2 × 1 surface. To prepare pure C 60 F 18 , a new method of fluorination of C 60 in solid-state reactions with transition metal fluo- rides (MnF 3 or K 2 PtF 6 ) was employed [3, 4]. Fluori- nation was conducted under Knudsen cell conditions with mass spectrometric identification of gaseous products. As a rule, the mass spectrum contained two main peaks which were attributed to C 60 and C 60 F 18 , and a few additional peaks which were attributed to the fragments of C 60 F 18 molecules that arose from the loss of some fluorine atoms under electron ionization. The deposition of C 60 F 18 molecules has been per- formed from Knudsen cell on a Si(100) – 2 × 1 surface kept at room temperature. The deposition rate was in the range of 0.05–0.1 ML/min. All experiments were carried out at room temperature using a home-built ultra high vacuum field ion-scanning tunneling micro- scope (base pressure 2 × 10 –11 Torr) equipped with standard surface preparation facilities [5]. Phosphorus doped Si(100) wafers with resistivity of 8–15 Ω cm were cut into pieces of 20 × 7 × 0.5 mm 3 and then ultra- sonically washed in acetone and distilled water. Sam- ples were mounted on a tantalum sample holder using “Ni-free” tools and the surface was cleaned by outgas- sing overnight at 650°C and then flashing at 1250°C Initial Stage of the Adsorption of Fluorofullerene Molecules on Si Surface ¶ A. I. Oreshkin a, e , R. Z. Bakhtizin b , P. Murugan c , V. Kumar d , N. Fukui e , T. Hashizume e, f , and T. Sakurai g a Faculty of Physics, Moscow State University, Moscow, 119992 Russia e-mail: oreshkin@spmlab.phys.msu.su b Department of Physical Electronics and Nanophysics, Bashkir State University, Ufa, 450074 Russia c Central Electrochemical Research Institute, 630006 Karaikudi, Tamil Nadu, India d Dr. Vijay Kumar Foundation, 1969 Sector 4, 122001 Gurgaon, Haryana, India e WPI-AIMR, Tohoku University 2-1-1 Katahira, Aoba-ku, 980-8577 Sendai, Japan f Advanced Research Laboratory, Hitachi, Ltd. Hatoyama, 350-0395 Saitama, Japan g Tohoku University 2-1-1 Katahira, Aoba-ku, 980-8577 Sendai, Japan Received August 6, 2010 Spatially resolved images of an individual C 60 F 18 fluorofullerene molecule on Si(100) – 2 × 1 surface have been obtained using scanning tunneling microscopy. Scanning tunneling microscopy results and ab initio cal- culations show that the fluorofullerene molecules interact with the Si(100) – 2 × 1 surface with F atoms point- ing down towards the surface. The adsorption energy of a C 60 F 18 molecule on Si(100) – 2 × 1 surface is ~12.1 eV, which is much higher than the adsorption energy of the same molecule on Si(111) – 7 × 7 surface (6.65 eV). C 60 F 18 molecules are located in the troughs in-between the dimer rows occupying the four-dimer site on Si(100) – 2 × 1 surface. DOI: 10.1134/S0021364010190033