In the last years the interest in using molecules as active elements in electronic devices has progressively increased. Patterning organic molecules on silicon surfaces is a promising way of controlling the electronic and transport properties of interfaces through the functionalization[1, 2].
We studied from first principles the electronic and transport properties of a hybrid silicon/organic/silicon interface. The interface is constituted of two silicon bulk leads and a conductor region made of a di-hydroxybiphenyl (C12H10O2) monolayer between two Si(111) surfaces.
The electronic structure calculations have been performed by means of a plane-waves implementation of the Density Functional Theory[3]. We present the results in terms of density of states and band structure of the conductor region, and we analyze the role played by molecule-molecule and silicon-molecules coupling.
Starting from the knowledge of the electronic structure, we calculated the electronic transport across the interface within the Landauer approach, using Maximally Localized Wannier Functions[4 - 6].
We report the quantum conductance and current across the interface: the analysis of two different configurations of the molecules on the surface allows us to understand how intermolecular interactions can affect the transport properties[7].
[1] J. Buriak, Chem. Rev. 102, 1271 (2002).
[2] T. Rakshit, G.-C. Liang, A. W. Ghosh and S. Datta, Nano Lett. 4, 1803 (2004).
[3] PWscf code by S. Baroni, A. Dal Corso, S. De Gironcoli and P. Giannozzi (2001), http://www.pwscf.org
[4] A. Calzolari, N. Marzari, I. Souza and M. Buongiorno Nardelli, Phys. Rev. B 69, 035108 (2004).
[5] WanT code by A. Calzolari, A. Ferretti, C. Cavazzoni, N. Marzari and M. Buongiorno Nardelli (2005), http://www.wannier-transport.org
[6] A. Ferretti, A. Calzolari, B. Bonferroni and R. Di Felice, J. Phys. Condens. Matter. 19, 036215 (2007).
[7] B. Bonferroni, et al., manuscript in preparation (2007).
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