US Patent 7273732 - Nanowire harvesting using doped sacrificial portions

http://www.freepatentsonline.com/7273732.html

This patent from Nanosys teaches a method to mass produce nanowires having more consistent characteristics based on the use of doping to create sacrificial portions of the nanowires that can be removed. Claim 1 reads:

1. A method of harvesting a nanowire, comprising the steps of: (a) growing a desired portion of the nanowire; (b) growing a sacrificial portion of the nanowire which is doped differently than the desired portion of the nanowire; (c) differentially removing the sacrificial portion of the nanowire; and (d) removing a growth stub from the desired portion of the nanowire.

US Patent 7256466 - Functionalized semiconductor nanowire

http://www.freepatentsonline.com/7256466.html

This patent from Harvard includes basic claims to functionalized semiconductor nanowires (including carbon nanotubes). It does have an early priority date (December 11, 2000) and while there is prior art for multiwall carbon nanotube functionalization such as for AFM tips the use of semiconductor nanowires can be more useful for sensing applications. Claim 1 reads:

1. An article comprising: a semiconductor nanowire comprising a core region and an outer region surrounding the core region, wherein the outer region is selectively functionalized with a chemical or biological species added to the nanowire after construction of the nanowire.

US Patent 7254151 - Nanowire laser

http://www.freepatentsonline.com/7254151.html

Forming lasers from semiconductor materials in the form of quantum (i.e. nano) wires has been accomplished several times in the prior art. This patent from Harvard alleges that lasing from nanowires based on "an electric signal from the substrate" is new. Claim 1 reads:

1. An apparatus, comprising: at least one nanoscale wire constructed and arranged to generate amplified stimulated emission of radiation, the at least one nanoscale wire including a first type semiconductor material; and a substrate, wherein the apparatus is constructed and arranged such that at least first carrier types are injected along at least a portion of a length of the at least one nanoscale wire, in response to an electric signal from the substrate, to facilitate generation of the amplified stimulated emission of the radiation.

Unfortunately quantum wire lasing prior art, which does work by electrical stimulation, such as

http://www.freepatentsonline.com/5363394.html

seems to have been overlooked (see column 5, lines 24-45).

US Patent 7233041 - Complementary nanowire inverter

http://www.freepatentsonline.com/7233041.html

This patent to Nanosys claims a structure analogous to a CMOS inverter but formed using aligned arrays of nanowires. Claim 1 reads:

1. An article comprising: at least a first and a second population of semiconducting nanowires disposed at distinct, non-overlapping regions from each other on a surface of a substrate, wherein nanowires in the first and second population each comprise a core and one or more shell layers disposed about said core; at least a first and a second pair of spaced-apart electrical contacts disposed at the distinct regions on the surface of the substrate, wherein at least two nanowires in each of the respective first and second populations of nanowires span and are electrically connected to the electrical contacts of each of the respective first and second pair of electrical contacts; and wherein nanowires in each of the first and second population of nanowires are substantially oriented in a first direction on the surface of the substrate.

US Patent 7230286 - Silicided bottom contact for nanowire FET

http://www.freepatentsonline.com/7230286.html

In vertical FETs the current flows through a vertical channel extending from a substrate in a direction perpendicular to the plane of the substrate. However, when nanowires are used for the vertical channels the contact resistance can be too high. This patent from IBM teaches using a silicide (i.e. metal-silicon compound) to reduce the contact resistance. Claim 1 reads:

1. A semiconductor structure comprising: a silicide contact layer located within, or on a portion of a semiconductor substrate; a plurality of nanowires located on said silicide contact layer; a gate dielectric surrounding said plurality of nanowires; a gate conductor located on said gate dielectric; and a source and drain located at each end of said nanowires.

US Patent 7228050 - Inorganic nanowires with orienting matrix

http://www.freepatentsonline.com/7228050.html

While high aspect ratio nanostructures (aka nanowires) can have favorable properties individually, when combined in a binding matrix these properties can be lost due to the disordered distribution of the nanowires or lack of cohesiveness between the nanowires. This patent from Nanosys teaches using a polymer or small molecule matrix to facilitate alignment of inorganic nanowires with a core/shell structure. Claim 1 reads:

1. A composite material, comprising: a plurality of discrete, preformed inorganic nanowires, wherein the inorganic nanowires comprise a core and one or more shell layers disposed about the core; and a small molecule or molecular matrix or a matrix comprising at least one polymer, which small molecule or molecular matrix or components thereof or which matrix comprising at least one polymer or components thereof are used to orient the nanowires.

US Patent 7225082 - Nanowire barcodes

http://www.freepatentsonline.com/7225082.html

While one of the common applications of quantum dots is in biomarker applications other nanoparticles may also be applied to this area. This patent from Oxonica discloses the use of segmented superparamagnetic nanowires that function as a barcode identification. Claim 20 reads:

20. A freestanding particle comprising 2 to 50 segments, wherein the particle length is from 20 nm to 50 microns, and the particle width is from 5 nm to 50 microns, and wherein at least one of said segments is comprised of a superparamagnetic compound.

US Patent 7220346 - Nanowire fabrication using stepped surface

http://www.freepatentsonline.com/7220346.html

One of the goals of nanowire fabrication is to increase the length to diameter ratio so that individual nanowires can be used to form connections over greater distances. This patent from the University of California used stepped surfaces of a substrate to assist in forming high aspect ratio nanowires. Claim 1 reads:

1. A method for preparing metallic nanometer scale wires comprising the steps of electrodepositing a metal at a step edge present on a stepped surface to form a wire, and removing the wire off of the stepped surface.

US Patent 7220310 - Nanopropeller

http://www.freepatentsonline.com/7220310.html

This patent claims yet another new type of nanostructure-a nanopropeller. The nanopropeller is taught to be useful in nanofluidic flow control and for improved AFM tips. Claim 1 reads:

1. A nanoscale junction array, comprising: a. an elongated nanowire; and b. a plurality of elongated nanobelts, each having a proximal end and an opposite distal end, the proximal end of each nanobelt being attached to a different location on the nanowire, each nanobelt extending radially away from the nanowire.

US Patent 7218004 - Fusing nanowires using crystal growth

http://www.freepatentsonline.com/7218004.html

Individually nanowires can have very useful electrical characteristics emerging from ballistic transport, quantum confinement, etc. However, when the nanowires are used in a clustered array the gaps between individual nanowires can reduce such usefulness. This patent from HP teaches a method that fuses nanowires so that clustered arrays of nanowires can maintain the characteristics of individual nanowires. Claim 1 reads:

1. A nanowire interconnection system comprising: means for applying nanowires on a surface of a substrate in a cluster; a solution having a controllable saturation condition, the solution comprising a crystal precursor solute dissolved in a solvent, the nanowires being immersed in the solution; and means for controlling the saturation condition of the solution, such that new crystal material is grown on a surface of the immersed nanowires to fuse together the nanowires of the cluster.

US Patent 7217946 - Nanowire fabrication using current induced overthickness

http://www.freepatentsonline.com/7217946.html

The desire for nanowire fabrication has led many to seek alternative methods to EUV lithography techniques such as nanoimprint lithography and self assembly. This patent teaches using currents between two electrodes to produce an effect that creates an array of parallel nanowires between the electrodes. Claim 1 reads:

1. Process for manufacturing nanowire structures, characterised in that it comprises: manufacture of a thin semiconductor film (1) extending between a first terminal (4) and a second terminal (5), and passage of a current between the first and the second terminals so as to form at least one continuous overthickness (R1, R2, R3) in the thin semiconductor film by migration of a fraction of the semiconductor material under the action of the current, the continuous overthickness being formed along the direction of the current that passes through the film.

US Patent 7211503 - Microscale to nanoscale electronics conversion using random interconnections

http://www.freepatentsonline.com/7211503.html

A variety of companies including Hewlett-Packard and Nanosys are working on using nanowires to form electronic memories, circuits and other devices. However, the processing used in forming the nanowires on a substrate (such as nanoimprint lithography, self-assembly, etc.) is very different from the processing (such as optical lithography) conventionally used in forming microscale wires and the two scales of wiring are thus usually formed in separate processing steps. Interconnection between microscale wires and nanowires thus requires new methodologies. This patent from HP proposes a microwire to nanowire addressing scheme based on randomly distributing nanowires across microwires and only using the portion of the nanowires achieving proper connections rather than trying to form the nanowires in a predetermined manner. Claim 1 reads:

1. A random microscale-to-nanoscale interface comprising: a number N of approximately parallel nanowires; a number M, where M>log.sub.2N, of approximately parallel microscale or sub-microscale address signal lines that are not parallel with respect to the N nanowires and that form a grid-like set of intersections with the N nanowires; and a random or pseudorandom distribution of interconnections within the grid-like set of intersections.

US Patent 7211464 - Uniform diameter nanowires

http://www.freepatentsonline.com/7211464.html

Electronic parameters of nanowires such as bandgap are dependent on the diameter of the nanowire. This patent originating from Harvard researches presents a very broad claim towards a method of growing nanowires of uniform diameter (give or take 20%) to achieve more consistent electronic device functionality. Claim 1 reads:

1. A method, comprising: growing a population of semiconductor nanowires, each having at least one portion having a smallest width less than 500 nanometers, catalytically from catalyst colloid particles having a variation in diameter of less than about 20% and being selected such that the population of semiconductor nanowires produced according to the method has a variation in diameter of less than 20%.

US Patent 7208094 - Nanowire growth from vertical surfaces

http://www.freepatentsonline.com/7208094.html

Nanotubes and nanowires are often grown from catalytic particles and can be formed in large arrays using such catalytic growth. However, this type of fabrication often results in arrays of vertically oriented nanowires which, while useful in some applications such as field emission displays, are often less useful in providing circuit interconnections. This patent from HP teaches growing nanowires from the side surfaces of a silicon substrate to establish horizontally oriented nanowires that may be more useful as interconnects or crossbar circuit elements. Claim 1 reads:

1. A method of growing a nanowire in a lateral direction comprising: forming vertical surfaces on or in a horizontal surface of a silicon substrate, the vertical surfaces being vertical relative to the horizontal surface, the vertical surfaces being (111) silicon lattice planes; activating a first vertical surface of the vertical surfaces with a nanoparticle catalyst; and growing a semiconductor nanowire laterally from the activated first vertical surface in a direction toward a second surface of the vertical surfaces, the second vertical surface being spaced from and opposite to the first vertical surface.

US Patent 7192533 - Multimaterial nanowire fabrication

http://www.freepatentsonline.com/7192533.pdf

Most often nanowire fabrication produces nanowires formed of the same type of material throughout the nanowire length but there is a desire for nanowires formed with multiple doping states or other divergent material properties to facilitate transistor, sensor or other device applications. This patent from Philips claims a basic method of constructing nanowires of pnp or npn material layer configurations. Claim 1 reads:

1. A method of manufacturing nanowires, comprising the steps of providing a patterned etching mask at a surface of a semiconductor substrate, and etching the semiconductor substrate so as to form nanowires In a direction substantially perpendicular to the surface of the semiconductor substrate, characterized in that the semiconductor substrate comprises a first layer of a first material, second layer of a second material, and a third layer of the first material, the second layer sandwiched between the first and third layers; and etching takes place through the first, second and third layers for forming the nanowires such that the nanowires comprise a first region of the first material, a second region of the second material and a third region of the first material.

Free Nanomaterials Database

I recently put together a database of US patents issued over the last 25 years having at least one claim reciting a nanoparticle (or quantum dot), a nanowire (or quantum wire), or a nanotube. The database is sortable based on filing year and listed assignee (patent holder) and provides a valuation index (also sortable) for each patent in the database based on the number of claim limitations. If anyone is interested in a copy send an E-mail to

blaise_mouttet@yahoo.com

with "Nanomaterial database" in the subject and I'll send you a copy.

US Patent 7190049 - Vertical nanowire array in polymer matrix

http://www.freepatentsonline.com/7190049.pdf

Co-polymer self-assembly is frequently being used to create templates to form large arrays of nanostructures on a substrate. This patent from the University of Massachusetts uses co-polymer self assembly to produce ultrahigh density nanowire arrays with high magnetic coercivity for magnetic storage applications. Claim 1 reads:

1. A nanoscale array comprising an electrically-conductive substrate and nanowires arranged in parallel on the substrate, the nanowires each having a diameter of 1.0 to 100 nanometers, and having a periodicity of 1.0 to 100 nanometers; and a polymer matrix between the nanowires, wherein the substrate is a metal substrate.

US Patent 7189635 - Interlaced nanowire fabrication

http://www.freepatentsonline.com/7189635.pdf

The fabrication of nanowires on a substrate often employs non-conventional manufacturing processes such as self-assembly and nanoimprint lithography. This patent from HP proposes a mixture of processes, the first of which forms a first array of parallel nanowires and the second of which reduces the diameters of the first nanowires to form a second set of nanowires between the first nanowires so as to allow for higher wire densities to be formed. Claim 1 reads:

1. A method of reducing feature dimensions of a nano-scale device comprising: consuming a surface of a device substrate, the device having a pattern of spaced apart first nanowires on the surface, the consumption reducing a dimension of the first nanowires; and forming a second nanowire in a trench between adjacent ones of the first nanowires, such that the device comprises a set of features that includes the first nanowires with the reduced dimension and the second nanowire spaced from the adjacent first nanowires by sub-trenches.

US Patent 7179561 - Nanowires on fuel cell membrane

http://www.freepatentsonline.com/7179561.pdf

This patent from Nanosys provides some basic claims toward the manufacture and structure of improved fuel cells including catalytic particles on the surface of nanowires to achieve higher efficiencies and power densities. Claim 1 reads:

1. A fuel cell comprising inorganic nanowires which are derivatized with at least a first functional group which binds to a metal catalyst deposited on a surface of the nanowires, wherein the nanowires are deposited or directly grown on a proton exchange membrane of the fuel cell.

US Patent 7164209 - Optimized Nanowire Spacing for Electrical Contacts

http://www.freepatentsonline.com/7164209.pdf

In order to assure connection between electrical contacts using metallic or semiconducting nanowires this patent from Nanosys proposes using nanowires at least twice as long as the separation between the electrical contacts. Claim 1 reads:

1. A nanowire based device comprising first and second electrical contacts disposed on a surface of a substrate and at least first and second nanowires positioned in contact with both of the first and second electrical contacts, wherein the first and second electrical contacts are separated from each other by a distance that is less than 50% of an average length of the first and second nanowires.