Atomic Manipulation on an Insulator Surface

Abstract

The manipulation of atomic and molecular species on metal surfaces with the scanning tunneling microscope (STM) operated at low temperature is a well established method for bottom-up nanofabrication [G. Meyer et al., Single Mol. 1, 79 (2000); N. Lorente, R. Rurali, H. Tang, J. Phys. Condens. Matter 17, S1049 (2005)], but is limited in its understanding and applications by restrictions inherent to the STM technique. These limitations can be overcome by using a dynamic scanning force microscope (SFM) for atomic manipulation that offers three major advantages compared to STM. First, the force microscope allows a quantification of the forces applied during the manipulation process (see Chap. 9), second, it facilitates manipulation at room temperature (see Chaps. 8 and 11) and, third, the technique allows manipulation on electrically insulating surfaces. However, examples for force controlled manipulation of atomic size species on an insulator surface are still scarce regarding experimental evidence [S. Hirth, F. Ostendorf, M. Reichling, Nanotechnology 17, S148 (2006); R. Nishi et al., Nanotechnology 17, S142 (2006)] as well as theoretical explanation [T. Trevethan et al., Phys. Rev. Lett. 98, 028101 (2007); T. Trevethan et al., Phys. Rev. B 76, 085414 (2007)]. Here we demonstrate the force controlled manipulation of water related defects on a CaF2 (111) surface by a raster scanning motion of the tip over a specific surface region. Manipulation is facilitated by repulsive forces exerted by approaching the tip very closely to the detects. We focus mainly on the presentation of manipulation results and discuss the circumstances that allow a control of the manipulation process. The CaF2 (111) surface is specifically well suited for such studies as this surface has been very well characterized by NC-AFM in previous studies [M. Reichling, C. Barth, Phys. Rev. Lett. 83, 768 (1999); C. Barth, M. Reichling, Surf. Sci. 470, L99 (2000); F.J. Giessibl, M. Reichling, Nanotechnology 16, S118 (2005); R. Hoffmann et al., J. Am. Chem. Soc. 127, 17863 (2005)] and contrast formation is understood on a quantitative level [A.S. Foster et al., Phys. Rev. Lett. 86, 2373 (2001); C. Barth et al., J. Phys. Condens. Matter 13, 2061 (2001); A.S. Foster et al., Phys. Rev. B 66, 235417 (2002)]. Furthermore, the geometric and electronic structures of this surface is well understood from a variety of theoretical simulations [A.V. Puchina et al., Solid State Commun. 106, 285 (1998); V.E. Puchin et al., J. Phys. Condens. Matter 13, 2081 (2001); Y. Ma, M. Rohlfing, Phys. Rev. B 75, 205114 (2007); Y. Ma, M. Rohlfing, Phys. Rev. B 77, 115118 (2008)]. Therefore, it can be expected that the experimental evidence of force controlled manipulation presented here will finally be fully explained by further theoretical modeling.