Active solid-state devices (e.g. – transistors – solid-state diode – Organic semiconductor material
Utility Patent
1998-06-02
2001-01-02
Crane, Sara (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Organic semiconductor material
C257S613000, C438S099000
Utility Patent
active
06169291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to unimolecular organic rectifiers, employing one or several layers of an organic molecule as a rectifier of electrical current, and methods of manufacturing the same, employing cryocooling of the formed organic layer to protect during deposition of a covering metal film, to provide an effective unimolecular rectifier.
BACKGROUND OF THE PRIOR ART
Unimolecular rectification of electrical current has been the focus of the computer industry for several years. Although expected to revolutionize that industry, application of unimolecular electrical rectifiers, referred to as the world's smallest telectronic devices, has been hampered by practical difficulties. In particular, the unimolecular layer suffers from weak formation on the metal electrodes, which causes the molecules to “turn around” in the presence of small voltages, under about one volt. In use, the molecules begin to tumble end over end to avoid the application of “high” electric fields.
Thus, while it was proposed in 1973 that a single organic molecule could be a rectifier of electrical current, Aviram. et al., Chem. Phys. Lett. 29, 277-283 (1974), this proposal was not verified for many years, despite drawing substantial attention. See, e.g., Metzger, Mater. Sci. & Eng. Rg. C3, 277-285 (1995). Sambles and co-workers used a Pt/multilayer/Mg/Al sandwich to find asymmetric currents through molecular multilayers. See, e.g., Geddes. et al., J. Appl. Phys. 71, 756-768 (1992) and Ashwell, et al. and Martin. et al., Phys. Rev. Lett. 70, 218-221 (1993).
Much of the difficulty encountered by Sambles and others is due to the fact that by using a variety of different metals, with different work functions on either side of the organic film, many different “Schottky barriers” could be formed, which mask and distort the electrical asymmetries due to the organic molecules themselves.
Nonetheless, uninolecular electronics are anticipated to revolutionize the computer industry, if the delicacy of the organic molecules employed in these inventions, under bias, can be addressed. These organic molecules are difficult to deposit onto metal electrodes, and their delicate electrical characteristics are easily damaged by the temperatures encountered in depositing a second electrode thereover.
Accordingly, it remains an object of those of skill in the art to provide an effective, reliable unimolecular electrical rectifier, and methods for fabricating the same.
SUMMARY OF THE INVENTION
The above objects, and others made more clear by the discussions set forth below, are achieved by the formation of a uninolecular organic rectifier using cryocooling to preserve the delicate electrical characteristics of the organic monolayer.
A conventional aluminum metal electrode is formed on silicon or other suitable substrate. This is conveniently achieved using a high-vacuum evaporator, or a film coater. Once the “bottom” electrode is formed, one or more layers of an organic molecule which preferably exhibits a ground-state zwitteronic electrical character, is deposited on top of the formed aluminum layer, through Langmuir-Blodgett film transfer. The formed organic layer is dried in a desiccator or evaporator, to eliminate water trapped between the aluminum layer and the organic layer(s), which will interfere with operation.
To preserve the delicate nature of the organic layer, the layer is cryocooled using liquid nitrogen, and then aluminum is deposited onto the cryocooled organic layer. Thereafter, contacts are formed connecting the two aluminum electrode layers, through eutectic contacts, to conductors such as gold wires.
REFERENCES:
patent: 3953874 (1976-04-01), Aviram et al.
patent: 5152805 (1992-10-01), Geddes et al.
Aviram, et al., Chem. Phys. Lett. 29, 277-283 (1974).
Metzger, Mater. Sci. & Eng. Rg. C3, 277-285 (1995).
Geddes, et al., J. Appl. Phys. 71, 756-768 (1992).
Martin, et al., Phys. Rev. Lett. 70, 218-221 (1993).
Ashwell, et al., Lower-Dimensional Systems and Molecular Electronics, vol B248, p. 647 (1991).
Geddes, et al., Appl. Phys. Lett. 56, 1916-1918 (1990).
Metzer, et al., J. Am. Chem. Soc. 119, 10455-10466 (1997).
Chen Bo
Metzger Robert M.
Crane Sara
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
The University of Alabama
LandOfFree
Unimolecular organic rectifier of electrical current does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Unimolecular organic rectifier of electrical current, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Unimolecular organic rectifier of electrical current will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2499637