Molecular switch junctions in silicon-organic molecule interface
D. Nozaki, C. Toher, F. Pump, and G. Cuniberti
Max Bergmann Symposium 2008
2008.11.04-06; Max Bergmann Center, Dresden, Germany
Since the success of the measurement of current conduction through individual molecules, molecular electronics has achieved a series of significant advances. Recently the integration of nanotechnology with biological systems has created the opportunity to use bio-recognition for the development of molecule-based devices such as sensitive bio-sensors. In particular, the silicon-organic molecule interface provides a promising platform for the development of such bio-molecule-based molecular devices. I this work, we explore the usability of organic molecules with bistable characteristics as reversibly tunable molecular switches in electrode/molecule/electrode configurations driven by external stimulations such as light  or current-pulse . We have modeled three kinds of molecular switch-junctions formed with silicon contacts and azobenzene derivatives which have bistable characteristics, i.e. both of cis- and trans-conformations. Using the non-equilibrium Green function (NEGF) approach  implemented with the density-functional-based tight-binding (DFTB) theory , we have analyzed a series of properties of the switch-junctions such as the electronic transmission, the on/off current and their ratio, potential energy surfaces as a function of reaction coordinate from cis- and trans-conformation. Furthermore, in order to investigate the stability of molecular switches in ambient conditions, we have performed molecular dynamics simulations (MD) at room temperature and calculated the time-dependent transmission fluctuations along the MD pathways . The numerical results have shown that transmission spectra in cis-conformations are more conductive than trans-conformations inside the bias window. I-V characteristics also lead to the same trends. Additionally, the calculations of time-dependent transmission fluctuations along with the MD pathways have shown that the transmission fluctuations in cis- and trans-conformations do not overlap with each other and can be distinguished at room temperature. Therefore, the azobenezene derivative-based molecular switches can be expected to work as robust organic switching components.
 M. del Valle, R. Gutierez, C. Tejedor, and G. Cuniberti, Nature Nanotech. 2, 176 (2007).
 H. Riel et al., Small 2, 977 (2006).
 A. Pecchia and A. Di Carlo, Rep. Prog. Phys. 67, 1497 (2004).
 T. Frauenheim et al., J. Phys. Cond.-Matt. 14, 3015 (2002).
 A. Pecchia, et. al., Phys. Rev. B 68, 235321 (2003).
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Prof. Dr. Gianaurelio Cuniberti
Institute for Materials Science
visitors and courier address:
01062 Dresden, Germany