AVS 53rd International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS2-TuM

Paper NS2-TuM4
Toward Stable Molecular Devices: Desorption of Cyclopentene from p-Si(100) with UHV-STM and Density Functional Theory

Tuesday, November 14, 2006, 9:00 am, Room 2020

Session: Nanoscale Manipulation and Assembly
Presenter: N.L. Yoder, Northwestern University
Authors: N.L. Yoder, Northwestern University
N.P. Guisinger, Northwestern University
M.C. Hersam, Northwestern University
Correspondent: Click to Email
In recent years, substantial progress has been made in the emerging field of molecular electronics. Of particular interest is the integration of molecular electronic devices with conventional silicon microelectronic technology. The presence of the energy band gap in silicon allows for resonant tunneling through individual molecules, leading to interesting effects such as room temperature negative differential resistance.@footnote 1@ Additionally, studies of organic molecule-silicon junctions can yield important insights into the feasibility of future hybrid molecule-silicon devices. In particular, the reliability of these molecular junctions is of critical importance to potential devices, and consequently warrants further investigation. Single cyclopentene molecules on silicon provide a useful test case, since the binding geometry has been studied both experimentally and theoretically. In this study, a combination of experimental and theoretical tools were employed to investigate the stability of cyclopentene molecules on a degenerately doped p-type Si(100) surface. Experiments were performed using a cryogenic ultra-high vacuum scanning tunneling microscope. At 80 K, cyclopentene desorbs from the surface at both positive and negative sample bias polarities over a range of tunneling currents. The desorption rate is roughly linear with tunneling current, indicating a single-electron/hole process. The desorption yield is a strong function of bias, and has turn-on voltage of -2.5 V at negative bias and 3.5 V at positive bias. The magnitude of the yield ranges from 2x10@super -12@ to 1x10@super -8@ events/electron at both polarities, which is 500-1000x smaller than the reported yields of Benzene on Si(100) and Chlorobenzene on Si(111). Density functional theory and reaction path calculations were performed in order to determine the details of the desorption process. @FootnoteText@ @footnote 1@N.P. Guisinger et al, Nano Letters 4, 55 (2004) and Proc. Nat. Acad. Sci. 102, 8838 (2005).