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Fabrication of nanoscale electrodes via on-chip electrodeposition

M. W. Wu* and L. L. Sohn

Dept. of Physics, Princeton University
Princeton, NJ 08544

This is an abstract for a presentation given at the
Seventh Foresight Conference on Molecular Nanotechnology.
There will be a link from here to the full article when it is available on the web.

 

Molecular-based electronics represents a new class of devices which can achieve 1) high-densities per chip; 2) truly three-dimensional architecture; and 3) high-speed operation. In addition, such electronics may exhibit quantum-mechanical phenomena, e.g.single-electron tunneling, at or near room temperature which are applicable to logic devices.

Key to realizing molecular-based electronics is the fabrication of metallic leads whose length scales are commensurate to the size of a single molecule (~1 nm). Such leads are necessary to interface and connect the molecules of interest. While efforts have been placed on electron-beam and scanning-probe lithographies and self-assembled structures, there has yet to be an appropriate method for achieving, with precision and high-yield, such length scales in metallic nanostructures. One promising strategy, however, is electrodeposition via aqueous solutions, i.e. electroplating [1, 2]. Here, metallic ions in solution are deposited onto the leads via an electrolytic chemical reaction. While successful in achieving nanometer resolution, this particular technique is limited to solutions which must contain the metal ions of interest and cannot be used to produce an arbitrary deposition profile.

We have developed a more flexible variation of the electrodeposition process. Unlike previous methods, ours employs an on-chip anode as the metal source and utilizes microliter quantities of a solution that initially does not contain the particular metal ion. The process can thus deposit metals in situ, producing separations less than 10 nm. Potential applications of our technique include nanofabrication processes requiring a low-metal ion concentration, localized electrodeposition, and the repair of damaged or malformed circuit interconnects in situ, the latter of which is currently not possible with standard lithographic techniques. The use of electrodeposited nanoscale electrodes as either quantum point contacts or metallic leads for a molecular junction may have potential applications in logic devices, both classical and quantum.

References

[1]
C. Z. Li and N. J. Tao. Quantum transport in metallic nanowires fabricated by electrochemical deposition/dissolution. Applied Physics Letters, 72(8):894-6, February 1998.

[2]
A. F. Morpurgo, C. M. Marcus, and D. B. Robinson. Controlled fabrication of metallic electrodes with atomic separation. Applied Physics Letters, 74(14):2084-6, April 1999.

*Corresponding Address:
Mingshaw Wu
Dept. of Physics, Princeton University
Jadwin Hall, Washington Road, Princeton, NJ 08544 USA
Phone: 609.258.1765; Fax: 609.258.0989
Email: mwwu@oberon.princeton.edu; Web: http://oberon.princeton.edu/~mwwu



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