Investigation of Hybrid Molecular/Silicon Memories With Redox-Active Molecules Acting as Storage Media

In this paper, a physical investigation of hybrid molecular/Si memory capacitor structures is proposed, where redox-active molecules act as storage medium. Fc and ZnAB3P porphyrin were grafted on (100) Si with both a direct bond and a chemical linker in order to investigate the electron transfer properties of the molecule/Si system. The chemical structures of the molecular layers were analyzed with X-ray photoelectron spectroscopy. Cyclic voltammetry and impedance spectroscopy were also performed on capacitor structures in order to characterize the charge transfer between the redox molecules and the Si and the effect of an organic linker on its rate. To explain our results, an original electrical model of molecule/Si memory structures is proposed. Calculated data are compared to impedance results for the cases of Fc either directly grafted or with linker. The model allows us to give a theoretical confirmation of the influence of the linker over the redox energy and on the time constant of the molecular capacitor. Finally, density functional theory calculations provide an in-depth physical insight of the effect of the linker over the Fc redox energy. The results obtained in this paper show the strong impact of the engineering of the redox molecules and their linker on the electron transfer properties.

[1]  G. Ghibaudo,et al.  Single electron effects and structural effects in ultrascaled silicon nanocrystal floating-gate memories , 2004, IEEE Transactions on Nanotechnology.

[2]  Jonathan S. Lindsey,et al.  Multiple-bit storage properties of porphyrin monolayers on SiO2 , 2004 .

[3]  Martin Kerber.  Energy distribution of slow trapping states in metal‐oxide‐semiconductor devices after Fowler–Nordheim injection , 1993 .

[4]  Bonnie A. Sheriff,et al.  A 160-kilobit molecular electronic memory patterned at 1011 bits per square centimetre , 2007, Nature.

[5]  O. Seitz,et al.  What is the Barrier for Tunneling Through Alkyl Monolayers? Results from n‐ and p‐Si–Alkyl/Hg Junctions , 2007 .

[6]  W. Read,et al.  Statistics of the Recombinations of Holes and Electrons , 1952 .

[7]  E. H. Nicollian,et al.  The si-sio, interface – electrical properties as determined by the metal-insulator-silicon conductance technique , 1967 .

[8]  F. Hauquier,et al.  Single-component and mixed ferrocene-terminated alkyl monolayers covalently bound to Si(111) surfaces. , 2006, The journal of physical chemistry. B.

[9]  Kuhr,et al.  Synthesis of "Porphyrin-linker-Thiol" molecules with diverse linkers for studies of molecular-based information storage , 2000, The Journal of organic chemistry.

[10]  M. Cossi,et al.  Measurement and DFT calculation of Fe(cp)(2) redox potential in molecular monolayers covalently bound to H-Si(100). , 2006, The journal of physical chemistry. B.

[11]  F. Matthias Bickelhaupt,et al.  Chemistry with ADF , 2001, J. Comput. Chem..

[12]  V. Misra,et al.  Modulation of drain current by redox-active molecules incorporated in Si MOSFETs , 2004, IEDM Technical Digest. IEEE International Electron Devices Meeting, 2004..

[13]  R. Zanoni,et al.  An AFM, XPS and electrochemical study of molecular electroactive monolayers formed by wet chemistry functionalization of H-terminated Si(1 0 0) with vinylferrocene , 2005 .

[14]  Francisco Zaera,et al.  Measurements of electron-transfer rates of charge-storage molecular monolayers on Si(100). Toward hybrid molecular/semiconductor information storage devices. , 2003, Journal of the American Chemical Society.

[15]  D. Vuillaume,et al.  Electronic structure of a heterostructure of an alkylsiloxane self-assembled monolayer on silicon , 1998 .

[16]  A. A. Yasseri,et al.  Diverse redox-active molecules bearing O-, S-, or Se-terminated tethers for attachment to silicon in studies of molecular information storage. , 2004, The Journal of organic chemistry.

[17]  Valence band tunneling model for charge transfer of redox-active molecules attached to n- and p-silicon substrates , 2007 .

[18]  D. Strukov,et al.  CMOL FPGA: a reconfigurable architecture for hybrid digital circuits with two-terminal nanodevices , 2005 .

[19]  Dominique Vuillaume,et al.  Properties of electronic traps at silicon/1-octadecene interfaces , 2001 .

[20]  C. Hu,et al.  Random telegraph noise in flash memories - model and technology scaling , 2007, 2007 IEEE International Electron Devices Meeting.

[21]  G. Ghibaudo,et al.  Degradation of floating-gate memory reliability by few electron phenomena , 2006, IEEE Transactions on Electron Devices.

[22]  R. Williams,et al.  Nano/CMOS architectures using a field-programmable nanowire interconnect , 2007 .

[23]  Roberto Cingolani,et al.  Projecting the nanoworld: Concepts, results and perspectives of molecular electronics , 2004 .

[24]  Q. Guo,et al.  Quantum-chemical predictions of absolute standard redox potentials of diverse organic molecules and free radicals in acetonitrile. , 2005, Journal of the American Chemical Society.