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Metal-free silicon–molecule–nanotube testbed and memory device


Work from several laboratories has shown that metal nanofilaments cause problems in some molecular electronics testbeds. A new testbed for exploring the electrical properties of single molecules has been developed to eliminate the possibility of metal nanofilament formation and to ensure that molecular effects are measured. This metal-free system uses single-crystal silicon and single-walled carbon nanotubes as electrodes for the molecular monolayer. A direct Si–arylcarbon grafting method is used. Use of this structure with π-conjugated organic molecules resulted in a hysteresis loop with current–voltage measurements that are useful for an electronic memory device. The memory is non-volatile for more than 3 days, non-destructive for more than 1,000 reading operations and capable of more than 1,000 write–erase cycles before device breakdown. Devices without π-conjugated molecules (Si–H surface only) or with long-chain alkyl-bearing molecules produced no hysteresis, indicating that the observed memory effect is molecularly relevant.

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Figure 1: A schematic of the Si–molecule–SWNT device and its fabrication process.
Figure 2: Structures of the molecules used in the Si–molecule–SWNT device.
Figure 3: Typical (V) characteristics of a Si–OPE 1–SWNT device.
Figure 4: The memory effect of a Si–OPE 1–SWNT device.
Figure 5: Arrhenius plots of the (V,T) test of a Si–OPE 1–SWNT device with a 5-μm diameter well showing little temperature dependence.
Figure 6: Plots demonstrating a fit with Fowler–Nordheim tunnelling in a Si–OPE 1–SWNT 5-μm-diameter-well device.


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This work was supported by the Defense Advanced Research Projects Agency through the Air Force Office of Scientific Research.

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Correspondence to James M. Tour.

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He, J., Chen, B., Flatt, A. et al. Metal-free silicon–molecule–nanotube testbed and memory device. Nature Mater 5, 63–68 (2006).

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