Catalyst – solid sorbent – or support therefor: product or process – Miscellaneous
Reexamination Certificate
2001-06-29
2004-10-19
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Miscellaneous
C502S263000, C438S726000
Reexamination Certificate
active
06806228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of providing a synthesis technique to grow bulk quantities of semiconductor nanowires at temperatures less than 500° C.
2. Description of the Prior Art
One-dimensional semiconductor fibers are useful for many applications ranging from probe microscopy tips to interconnections in nanoelectronics. By “one-dimensional” it is meant that the fibers have extremely small diameters, approaching 40 Ångstroms. The fibers may be termed “nanowires” or “whiskers.” Several methods are known for synthesis of these fibers. Included are VLS (vapor-liquid-solid) growth, laser ablation of silicon and silicon oxide species and combinations of these techniques.
In VLS growth, a liquid metal cluster or catalyst acts as the energetically favored site of absorption of gas-phase reactants. The cluster supersaturates and grows a one-dimensional structure of the material. A VLS method has been used to grow silicon nanowires by absorption of silane vapor on a gold metal surface. Variations of this methods have been used to produce other semiconductor fibers.
One variation is laser ablation. In this technique, the silicone species, such as SiO
2
, is ablated to the vapor phase by laser excitation.
SUMMARY OF THE INVENTION
The present invention provides a method of synthesizing semiconductor fibers by placement of gallium or indium metal on a desired substrate, placing the combination in a low pressure chamber at a vacuum from 100 mTorr to one atmosphere pressure in an atmosphere containing desired gaseous reactants, raising the temperature of the metal to a few degrees above its melting point by microwave excitation, whereby the reactants form fibers of the desired length. When the metal is gallium, a temperature of about at least 50° C. is sufficient, preferably near 300° C. for best solubility and mobility within the melt. When the metal is indium, a temperature of about 200° C. is preferred. Preferably the substrate is silicon, most preferably silicon comprising an electronically useful pattern; the metal is gallium, the gaseous reactant is hydrogen, and the fibers formed comprise SiH
x
. The gallium metal may be applied either in solid or droplet form or in the form of patterned droplets for patterning silicon microwires. Other forms of gallium droplet patterns may also include droplets in two dimensional and three dimensional channels for directed growth.
Another preferable substrate is germanium with hydrogen as gaseous reactant. The reactant hydrogen will form germane, GeH
x
in the gas phase which upon decomposition on a gallium substrate results in the deposition of germanium into gallium droplets. The dissolved germanium grows out as germanium nanowires.
Other semiconductors materials may be synthesized according to the methods of this invention. In each case, gallium or indium metal is used as the absorption sit-catalyst. Where the substrate is not readily vaporized to provide a gaseous reactant, a vapor substrate will be added to the reactive atmosphere. For example, GaAs substrates may be used, with a gallium drop and nitrogen in the gas phase, to grow GaN nanofibers.
These and other objects of the present invention will be more fully understood from the following description of the invention.
REFERENCES:
patent: 4886683 (1989-12-01), Hoke et al.
patent: 5334296 (1994-08-01), Henkens et al.
patent: 5381753 (1995-01-01), Okajima et al.
patent: 5725674 (1998-03-01), Moustakas et al.
patent: 5858862 (1999-01-01), Westwater et al.
patent: 5922183 (1999-07-01), Rauh
patent: 5962863 (1999-10-01), Russell et al.
patent: 6033866 (2000-03-01), Guo et al.
patent: 6051849 (2000-04-01), Davis et al.
patent: 6063246 (2000-05-01), Wolfe et al.
patent: 2086121 (1990-03-01), None
patent: 11177134 (1999-07-01), None
Publication No. WO026422A1 for “High Purity Gallium For Preparation of Compound Semiconductor, and Method and Apparatus for Purifying the Same” by Yamamura et al., published on May 11, 2000.
Publication No. WO9965068A1 for “Fabrication of Gallium Nitride Semiconductor Layers by Lateral Growth from Trench Sidewalls” by Zheleva et al., published on Dec. 16, 1999.
Publication No. WO9944224A1 for “Method of Fabricating Gallium Nitride Semiconductor Layers by Lateral Overgrowth Through Masks, and Gallium Nitride Semiconductor Structures Fabricated Thereby” by Davis et al., published on Sep. 2, 1999.
Y.F. Zhang, Y.H. Tang, N. Wang, C.S. Lee, I. Bello, S.T. Lee “One-Dimensional Growth Mechanism of Crystalline Silicon Nanowires”, Journal of Crystal Growth 197 (1999) 136-140, no month.
J. Westwater, D.P. Gosain, S. Tomiya, S. Usui, and H. Ruda “Growth of Silicon Nanowires Via Gold/Silane Vapor-Liquid Solid Reaction”, J. Vac. Sci. Technol. B 15(3), May/Jun. 1997, 554-557.
A.M. Morales and C.M. Lieber “A Laser Ablation Method for the Synthesis of Crystalline Semiconductor Nanowires”, Science, vol. 279, Jan. 9, 1998, 208-211.
H.F. Yan, Y.J. Xing, Q.L. Hang, D.P. Yu, Y.P. Wang, J. Xu, Z.H. Xi, S.Q. Feng “Growth of Amorphous Silicon Nanowires Via a Solid-Liquid-Solid Mechanism”, Chemical Physics Letters 323 (2000) 224-228, no date.
J.L. Gole and J.D. Stout, W.L. Rauch and Z.L. Wang “Direct Synthesis of Silicon Nanowires, Silica Nanospheres, and Wire-Like Nanosphere Agglomerates”, Applied Physics Letters, vol. 76, No. 17, Apr. 24, 2000, 2346-2348.
J.D. Holmes, K.P. Johnston, R.C. Doty, B.A. Korgel “Control of Thickness and Orientation of Solution-Grown Silicon Nanowires”, Science, vol. 287, Feb. 25, 2000, 1471-1473.
P. Scheier, J. Marsen, M. Lonfat, W. Schneider, K. Sattler “Growth of Silicon Nanostructures on Graphite”, Surface Science 458 (2000, 113-122, no date.
D.P. Yu, Z.G. Bai, Y. Ding, Q.L. Hang, H.Z. Zhang, J.J. Wang, Y.H. Zou, W. Qian, G.C. Xiong, H.T. Zhou, and S.Q. Feng “Nanoscale Silicon Wires Synthesized Using Simple Physical Evaporation”, Applied Physics Letters, vol. 72, No. 26, Jun. 29, 1998, 3458-3460.
Y.F. Zhang, Y.H. Tanh, N. Wang, D.P. Yu, C.S. Lee, I. Bello, and S.T. Lee “Silicon Nanowires Prepared by Laser Ablation at High Temperature”, Applied Physics Letters, vol. 72, No. 15, Apr. 13, 1998, 1835-1837.
D.P. Yu, Y.J. Xing, Q.L. Hang, H.F. Yan, J. Xu, Z.H. Xi, S.Q. Feng “Controlled Growth of Oriented Amorphous Silicon Nanowires Via a Solid-Liquid-Solid (SLS) Mechanism”, Physica E 9 (2001) 305-309, no date.
Lieber, “One-Dimensional Nanostructures: Chemistry, Physics & Applications”, Solid State Communications, vol. 107, No. 11, 607-616, no date.
Sharma et al. “Novel Vapor-Liquid-Solid Synthesis Method for Carbon Nanostructures”, presented on CD and at Carbon2001 Conference at The University of Kentucky, Lexington, KY in Jul. of 2001.
Zhang et al. “Morphology and Growth Mechanism Study of Self-Assembled Silicon Nanowires Synthesized by Thermal Evaporation”, Chemical Physics Letters 337 (2001) 18-24, Mar. 30, 2001.
Wu et al. “Germanium Nanowire Growth Via Simple Vapor Transport”, Chem. Mater. 2000, 12, 605-607, no month.
Sharma Shashank
Sunkara Mahendra Kumar
Carrithers David W.
Carrithers Law Office
Johnson Edward M.
Silverman Stanley S.
University of Louisville
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