Bramanti A.

Demarchi D.

Graziano M.

Piccinini G.

Pulimeno A.

English

PULIMENO, AZZURRA

GRAZIANO, MARIAGRAZIA

DEMARCHI, DANILO

PICCININI, GIANLUCA

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

03 August 2020POLITECNICO DI TORINORepository ISTITUZIONALEBis-ferrocene molecules for QCA : a write-in method / Pulimeno A.; Graziano M.; Demarchi D.; Bramanti A.; Piccinini G..- (2010). ((Intervento presentato al convegno International Meeting on Molecular Electronics tenutosi a Grenoble (Fr) nel6-10 December.OriginalBis-ferrocene molecules for QCA : a write-in methodPublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2375482 since:Bis-ferrocene molecules for QCA : a write-in methodA. Pulimeno  a   , M. Grazianoa, D. Demarchia , A. Bramantib , G. Piccininiaa Department of Electronics – Politecnico di Torino, C.so Duca degli Abruzzi 24, I-10129, Torino, Italyb STMicroelectronics Srl, Distretto tecnologico-University of Lecce, Via per Arnesano 16, I-73100, Lecce,  Italy Quantum-dot Cellular Automata (QCA) is a new paradigm for digital computing that, theoretically, allows very high operating frequency and significant power consumption reduction [1]. According to the Lent theory [2], a possible implementation of a QCA cell could be physically obtained with a molecular system with two or more  redox-centers, where the charge configuration encodes the binary information and the electrostatic repulsion provides the device-device interaction. Ideal molecular systems have been studied [3, 4], while we present a method to use a bis-ferrocene molecule (Fig. 1) [5] synthesized ad hoc to implement a QCA device with two redox-centers (represented by the ferrocenes): they are separated by a central carbazole bridge, that provides the isolation between the two dots. Though not conductive, this molecule can be influenced by an external electric field in order to change its internal state (HOMO), encoding thus the “0”, “1” and NULL logic value. From an ab initio analysis, the HOMO of this molecule in its ground state is de-localized along the molecule and mainly on the carbazole (Fig. 1A). Applying an electric field along the x axis, we force a “1” or “0” state (Fig. 1B and 1C, respectively)  obtained by the HOMO localization  around one of the two ferrocenes.  An electric  field applied along the y axis has the effect of localizing the HOMO on the carbazole, forcing the molecule into a NULL state. We found that an electric field in the same direction but with opposite sign localizes the HOMO around the  two ferrocenes,  enhancing  the  molecule  sensitivity  to  assume one of  the  two logical  states  in presence of a driver (a neighbour identical molecule). These results are important for what concerns the clock issues [6]. The applied electric field is of the order of 1 V/nm and could be easily obtained with a nanogap of about  few nanometres:  we  are  investigating  the  possibility  to  use  this  nanostructure  in  combination  with conductive molecules for the read-out of the QCA cell state.References(1) C. S. Lent, P. D. Tougaw, and W. Porod, IEEE PhysComp '94, 1994, pp- 5-13.(2) C. S. Lent, P. D. Tougaw, W. Porod, and G. H. Bernstein, Nanotechnology, 1993, Vol. 4, pp. 49–57.(3) B. Isaksen, C. S. Lent and M. Lieberman, J. Am. Chem. Soc. 2003, Vol. 125, pp. 1056–1063.(4) C. S. Lent and B. Isaksen, Electron Devices, IEEE Transactions on, 2003, Vol. 50, pp. 1890–1896.(5) L. Zoli,  PhD Dissertation, Università di Bologna, 2010.(6) V. Vankamamidi, M. Ottavi, and F. Lombardi, IEEE-NANO 2006, 2006, Vol. 1, pp 343–346.FiguresFigure 1. Bis-ferrocene QCA molecule: ground state HOMO (A); HOMOs of logical state “1” (B) and “0” (C).

Bis-ferrocene molecules for QCA : a write-in method

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Bis-ferrocene molecules for QCA : a write-in method

Bis-ferrocene molecules for QCA : a write-in method

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