AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM1-ThA

Paper EM1-ThA9
Ag Islands Decorated by C@sub 60@

Thursday, November 16, 2006, 4:40 pm, Room 2001

Session: Contacts to Organic and Molecular Devices
Presenter: C. Tao, University of Maryland, College Park
Authors: C. Tao, University of Maryland, College Park
T.J. Stasevich, University of Maryland, College Park
T.L. Einstein, University of Maryland, College Park
E.D. Williams, University of Maryland, College Park
Correspondent: Click to Email
It is increasingly clear that a great challenge in nanoscale electronics will be understanding and controlling the interaction between the active nanoscale element and the conductive electrodes in devices. At nanoscale structural changes involving the displacement of even a single metal atom will be closely related to the electronic properties and reliability. Here I will introduce our study on a specific metal-molecule interface formed at Ag monolayer islands decorated by C@sub 60@. At room temperature, equilibrium monolayer islands on clean Ag(111) surfaces are hexagonal. At extremely low coverage of C@sub 60@, C@sub 60@ molecules are found preferentially at sections of the island edge near corners. Individual C@sub 60@ is found at different position in sequential images. When more C@sub 60@ is deposited, C@sub 60@ molecules form more stable chains along the Ag island edge near the corners of the island. The shape of the islands changes at this point with smoother corners. As coverage increases further, C@sub 60@ chains become longer and the hexagonal islands become round. By controlling C@sub 60@ coverage, we can make Ag island edges fully covered by C@sub 60@ chains, which become closed rings. The equilibrium shape of Ag islands decorated by the surrounding C@sub 60@ ring is approximately circular and shows dynamic thermal fluctuations. The mechanism for C@sub 60@ distribution and shape change of islands will be discussed in the context of the 2D equilibrium crystal shape (ECS). By rapid STM scanning, we obtain sequential images of the C@sub 60@ rings and analyze the corresponding dynamic properties. The shape fluctuation of C@sub 60@ rings are clearly displayed by movies made of sequential images. Quantitative analysis of the shape fluctuation using correlation functions will be presented, and discussed in terms of the correlated motion of the C@sub 60@ molecules and underlying Ag atoms. @FootnoteText@ --Supported by NSF, MRSEC at the University of Maryland.