Fabrication of Nanowires

Abstract

This disclosure relates to a system and method for creating nanowires. A nanowire can be created by exposing layers of material in a superlattice and dissolving and transferring material from edges of the exposed layers onto a substrate. The nanowire can also be created by exposing layers of material in a superlattice and depositing material onto edges of the exposed layers.

1 . A system comprising: 
 a superlattice having multiple alternating layers including first alternating layers of a first material and second alternating layers of a second material, at least one layer of the multiple alternating layers having a length, a thickness, and a depth, the multiple alternating layers being deposited in a direction substantially parallel to the thickness;    wherein: 
 the multiple alternating layers have a first surface that extends substantially parallel to the thickness, the first surface including a portion of the first alternating layers and the second alternating layers; and  
 the multiple alternating layers having a second surface that is physically separated from the first surface, the second surface for electrical communication with the multiple alternating layers.  
   
   
   
       2 . The system of  claim 1 , wherein the thickness of at least one of the multiple alternating layers is nanometers in scale.  
   
   
       3 . The system of  claim 1 , wherein the second surface is in electrical communication with the multiple alternating layers.  
   
   
       4 . The system of  claim 1 , wherein the second surface is not in electrical communication with the multiple alternating layers.  
   
   
       5 . The system of  claim 1 , wherein the thickness of two or more of the multiple alternating layers is less than 50 nanometers.  
   
   
       6 . The system of  claim 1 , wherein the thickness of two or more of the multiple alternating layers is less than 15 nanometers.  
   
   
       7 . The system of  claim 1 , wherein the length of two or, more of the multiple alternating layers is from nanometers in scale to up to centimeters in scale.  
   
   
       8 . The system of  claim 1 , wherein the first alternating layers are conductive at the first surface and the second surface.  
   
   
       9 . The system of  claim 1 , wherein the first alternating layers are conductive at the first surface and the second surface and the second alternating layers are not conductive at the first surface.  
   
   
       10 . The system of  claim 1 , wherein the second material is conductive at the second surface but is sufficiently insulated at the first surface to be non-conductive at the first surface.  
   
   
       11 . The system of  claim 1 , wherein the second material is conductive at the second surface but is sufficiently oxidized, nitrided, or coated by an insulator at the first surface to be non-conductive at the first surface.  
   
   
       12 . The system of  claim 1 , wherein the first material and the second material have different oxidation rates.  
   
   
       13 . The system of  claim 1 , wherein the first material and the second material have different nitridation rates.  
   
   
       14 . The system of  claim 1 , wherein the first material is conductive, the second material is non-conductive, and the second surface exposes two or more of the first alternating layers.  
   
   
       15 . The system of  claim 1 , wherein, at the first surface, the first material is coated with a nanoscopically thin coating of one or more other materials.  
   
   
       16 . The system of  claim 1 , wherein the first material is tantalum, the second material is aluminum oxide, and the second surface exposes two or more of the first alternating layers.  
   
   
       17 . The system of  claim 1 , wherein the first material is gold and the second material is tantalum.  
   
   
       18 . The system of  claim 1 , wherein the first material and the second material are in epitaxial relationship.  
   
   
       19 . The system of  claim 1 , wherein one of the first material or the second material is semiconducting.  
   
   
       20 . The system of  claim 1 , wherein the first material is a first type of semiconducting material and the second material is a second type of semiconducting material.  
   
   
       21 . The system of  claim 1 , wherein the first material is a first type of semiconducting material and the second material is a second type of semiconducting material, wherein the first type and the second type have different dopant species or concentrations.  
   
   
       22 . The system of  claim 1 , wherein the first surface is planar.  
   
   
       23 . The system of  claim 1 , wherein the second surface is planar.  
   
   
       24 . A system comprising: 
 a superlattice having multiple alternating layers of a first material and a second material, at least one layer of the multiple alternating layers having a length, a thickness, and a depth, the multiple alternating layers being deposited in a direction substantially parallel to the thickness;    wherein: 
 at least one of the multiple alternating layers of the first material has a first surface that extends substantially parallel to the thickness;  
 at least one of the multiple alternating layers of the second material having a second surface that extends substantially parallel to the first surface, and wherein the second surface is offset from the first surface; and  
 the multiple alternating layers having a third surface, the third surface being physically remote from the first surface and the second surface, the third surface for electrical communication.  
   
   
   
       25 . The system of  claim 24 , wherein the third surface is in electrical communication with an electrical power source or sink.  
   
   
       26 . The system of  claim 24 , wherein the thickness of at least one of the multiple alternating layers is nanometers in scale.  
   
   
       27 . The system of  claim 24 , wherein the length of two or more of the multiple alternating layers is from nanometers in scale to up to centimeters in scale.  
   
   
       28 . The system of  claim 24 , wherein the second material is conductive at the second surface and the first material is not conductive at the first surface.  
   
   
       29 . The system of  claim 24 , wherein the second material is conductive, the first material is non-conductive, and the third surface exposes two or more of the multiple alternating layers of the second material.  
   
   
       30 . The system of  claim 24 , wherein the first surface and the second surface appear corrugated when viewed along a line perpendicular to the thickness and parallel to the length.  
   
   
       31 . The system of  claim 30 , wherein the corrugation has a stepped-square appearance.  
   
   
       32 . The system of  claim 30 , wherein the corrugation has a sawtooth appearance.  
   
   
       33 . The system of  claim 30 , wherein the corrugation has a sine-wave appearance.  
   
   
       34 . The system of  claim 24 , wherein the thickness of two or more of the multiple alternating layers is less than 50 nanometers.  
   
   
       35 . The system of  claim 24 , wherein the thickness of two or more of the multiple alternating layers is less than 15 nanometers.  
   
   
       36 . The system of  claim 24 , wherein the first material and the second material have different etch rates.  
   
   
       37 . The system of  claim 24 , wherein the first material and the second material are single-crystalline and epitaxial with respect to each other.  
   
   
       38 . A system comprising: 
 a superlattice having multiple alternating layers of two or more conductive materials alternating with one or more other materials, at least one of the multiple alternating layers having a length, a thickness, and a depth, the multiple alternating layers being deposited in a direction substantially parallel with the thickness;    wherein: 
 the multiple alternating layers of the conductive materials have a first set of exposed faces and the multiple alternating layers of the other materials have a second set of exposed faces, the first set of exposed faces being offset from the second set of exposed faces in a direction taken perpendicular to the thickness.  
   
   
   
       39 . The system of  claim 38 , wherein the length of two or more of the multiple alternating layers are from nanometers in scale to up to centimeters in scale.  
   
   
       40 . The system of  claim 38 , wherein the thickness of two or more of the multiple alternating layers is nanometers in scale.  
   
   
       41 . The system of  claim 38 , wherein the thickness of two or more of the multiple alternating layers is less than 15 nanometers.  
   
   
       42 . The system of  claim 38 , wherein the multiple alternating layers have a surface for electrical communication.  
   
   
       43 . The system of  claim 38 , wherein the multiple alternating layers have a surface that provides for electrical communication with an electrical power source or sink.  
   
   
       44 . The system of  claim 38 , wherein a first of the two or more conductive materials includes tantalum and a second of the two or more conductive materials includes gold.  
   
   
       45 . The system of  claim 38 , wherein a first of the two or more conductive materials includes tantalum and a second of the two or more conductive materials includes nickel.  
   
   
       46 . The system of  claim 38 , wherein the two or more conductive materials consist of two conductive materials.  
   
   
       47 . The system of  claim 38 , wherein the two or more conductive materials consist of three or more conductive materials.  
   
   
       48 . The system of  claim 38 , wherein the other materials are non-conductive.  
   
   
       49 . The system of  claim 38 , wherein the other materials includes aluminum.  
   
   
       50 . The system of  claim 38 , wherein the other materials includes aluminum oxide.  
   
   
       51 . The system of  claim 38 , wherein the other materials are semiconducting.  
   
   
       52 . A method comprising: 
 fabricating nanometer-thickness wires by:    exposing, to ions of a first conductive material, a working surface of a superlattice having alternating layers of a second conductive material and one or more other materials, the working surface comprising exposed edges of the alternating layers, the exposed edges having a thickness and a length, and    electrochemically depositing the ions on or near the exposed edges of the second conductive material layers to create wires of the first conductive material.    
   
   
       53 . The method of  claim 52 , wherein the electrochemically depositing includes creating a voltage difference between the exposed edges of the second conductive material layers and a bath containing the ions.  
   
   
       54 . The method of  claim 52 , further comprising treating the working surface to cause the exposed edges of the other materials to be non-conductive.  
   
   
       55 . The method of  claim 52 , further comprising oxidizing the working surface to oxidize the exposed edges of the other materials to be non-conductive.  
   
   
       56 . The method of  claim 52 , further comprising etching the working surface to erode the exposed edges of the second conductive material to be a distance away from the working surface along a depth perpendicular to the length and the thickness.  
   
   
       57 . The method of  claim 52 , further comprising etching the working surface to erode the exposed edges of the second conductive material to be a distance away from the exposed edges of the other materials along a depth perpendicular to the thickness and the length, and wherein the depositing is performed until the wires fill up the distance between the exposed edges of the second conductive material and the working surface.  
   
   
       58 . The method of  claim 52 , wherein the electrochemically depositing includes: 
 creating a voltage difference between the exposed edges of the second conductive material layers and a bath containing the ions, and wherein the creating the voltage difference includes:    creating a connecting surface and connecting the connecting surface to a first voltage source; and    connecting a second voltage source to the bath containing the ions.    
   
   
       59 . The method of  claim 52 , wherein the exposing the exposed edges of the second conductive material layers to the ions of the first conductive material includes immersing the working surface in a bath containing the ions.  
   
   
       60 . The method of  claim 52 , further comprising applying a thin, low-adhesion layer to the working surface that does not substantially interfere with a conductive property of the exposed edges of the second conductive material layers.  
   
   
       61 . The method of  claim 52 , further comprising removing the exposed edges of the second conductive material layers and transferring them to the substrate as nanowires.  
   
   
       62 . The method of  claim 52 , further comprising: 
 applying a thin, low-adhesion layer to the exposed edges that does not substantially interfere with a conductive property of the exposed edges of the second conductive material layers prior to depositing the ions;    providing a substrate having a high-adhesion layer;    contacting the wires that are on the exposed edges of the second conductive material layers onto the high-adhesion layer; and    removing the exposed edges of the second conductive material layers to release the wires from the exposed edges of the second conductive material layers.    
   
   
       63 . The method of  claim 52 , further comprising: 
 providing a substrate having a high-adhesion layer;    contacting the wires that are on the exposed edges of the second conductive material layers onto the high-adhesion layer; and    removing the exposed edges of the second conductive material layers to leave the wires on the high-adhesion layer of the substrate.    
   
   
       64 . The method of  claim 52 , further comprising: 
 applying, prior to the depositing, a thin, first adhesion layer to the exposed edges that does not substantially interfere with a conductive property of the exposed edges of the second conductive material layers;    providing a substrate having a second adhesion layer, the second adhesion layer having a higher coefficient of adhesion with respect to the wires than the first adhesion layer;    contacting the wires that are on the exposed edges of the second conductive material layers onto the second adhesion layer; and    removing the exposed edges of the second conductive material layers to leave the wires on the second adhesion layer.    
   
   
       65 . A method for fabricating nanometer-thickness wires, comprising: 
 exposing, to a solution of charged molecules or charged nano-objects, a working surface of a superlattice having alternating layers of a conductive material and one or more other materials, the working surface comprising exposed edges of the alternating layers, the exposed edges having a thickness and a length; and    electro-phoretically depositing the charged molecules or charged nano-objects on or near the exposed edges of the conductive material layers, there to create wires made of molecules or nano-objects.    
   
   
       66 . The method of  claim 65 , wherein the charged molecules or charged nano-objects include ionized inorganic molecules, ionized organic molecules, ionized biological molecules, ionized polymers, charged metal, semiconductor or insulating nanoparticles.  
   
   
       67 . A method for fabricating nanometer-thickness wires, comprising: 
 exposing, to a bath of water having a dissolved chemical, a working surface of a superlattice having alternating layers of a conductive material and one or more other materials, the working surface comprising exposed edges of the alternating layers, the exposed edges having a thickness and a length; and    inducing a chemical reaction between the dissolved chemical and water, thereby inducing electrolytic deposition of a reaction product of the reaction on or near the exposed edges of the conductive material layers, there to create wires made of the reaction product.    
   
   
       68 . The method of  claim 67 , wherein the reaction product includes oxides and ceramics.  
   
   
       69 . A method comprising: 
 fabricating nanometer-thickness wires by:    etching a working surface of a superlattice having alternating layers of one or more conductive materials with layers of one or more other materials, the other materials having a higher etch rate than the conductive materials, the working surface comprising exposed edges of the alternating layers, at least one of the exposed edges having a thickness and a length, with the thickness being nanometers in scale, wherein the etching the working surface preferentially erodes the other material layers to cause the exposed edges of the one or more conductive material layers to be offset from the exposed edges of the other material layers; and    using electrochemical deposition to dissolve the one or more conductive materials from the exposed edges of the conductive material layers and apply the dissolved materials onto a conductive substrate.    
   
   
       70 . The method of  claim 69 , wherein the applying the dissolved materials includes applying the dissolved materials onto an insulated layer of the conductive substrate.  
   
   
       71 . The method of  claim 69 , wherein the using is performed by: 
 placing the exposed edges of conductive material layers within nanometers to tens of nanometers of the insulated layer of the conductive substrate and within an electrolyte capable of carrying ions of the one or more conductive materials; and    creating a voltage difference between the exposed edges of the one or more conductive material layers and the conductive substrate.    
   
   
       72 . The method of  claim 69 , wherein the using is performed by: 
 placing the exposed edges of conductive material layers within nanometers to tens of nanometers of the insulated layer of the conductive substrate and within an electrolyte capable of carrying ions of the one or more conductive materials;    attaching the alternating layers to a first voltage source having a first voltage; and    attaching the conductive substrate to a second voltage source having a second voltage different from the first voltage.    
   
   
       73 . A method comprising: 
 fabricating nanometer-thickness wires by:    providing a working surface of a superlattice having alternating layers of one or more conductive materials with layers of one or more other non-conductive materials, the working surface being substantially planar and comprising exposed edges of the alternating layers, at least one of the exposed edges having a thickness and a length, with the thickness being nanometers in scale;    providing a substrate having a conducting thin-film surface layer;    immersing the working surface and the substrate in an electrolyte capable of carrying ions of the conducting thin-film surface layer; and    using electrochemical etching to dissolve part of the conducting thin-film surface layer locally and re-deposit the part of the conducting thin-film surface layer on the exposed edges of the conductive material layers.    
   
   
       74 . The method of  claim 73 , wherein the conducting thin-film surface layer and the substrate are separated by an insulator.  
   
   
       75 . The method of  claim 73 , wherein the using includes: 
 placing the exposed edges of the conductive material layers within nanometers to tens of nanometers of the conducting thin-film surface layer; and    creating a voltage difference between the exposed edges of the one or more conductive material layers and the conducting thin-film surface layer.    
   
   
       76 . A computer readable medium having computer executable instructions for performing steps comprising: 
 fabricating nanometer-thickness wires by:    placing, within nanometers to tens of nanometers of an insulating layer of a conductive substrate and within an electrolyte capable of carrying ions of one or more conductive materials, a working surface that exposes edges of alternating layers, including a first set of layers of one or more conductive materials and a second set of layers of one or more other materials, the exposed edges having a thickness and a length, with the thickness being nanometers in scale; and    creating a voltage difference between the exposed edges of the conductive material layers and the conductive substrate.    
   
   
       77 . A method comprising: 
 fabricating a superlattice by:    applying onto a substrate, layers of two or more conductive materials with a first thickness less than 50 nanometers alternating with one or more other materials with a second thickness less than 50 nanometers, to create alternating layers of the conductive materials and the other materials; and    providing a working surface including a first set of edges made from the conductive materials and a second set of edges made from the other materials, the first set of edges extending substantially parallel to each other and the second set of edges.    
   
   
       78 . The method of  claim 77 , wherein the applying is performed so that the first thickness is less than 20 nanometers.  
   
   
       79 . The method of  claim 77 , wherein the applying is performed so that the first thickness is less than 20 nanometers and the second thickness is less than 20 nanometers.  
   
   
       80 . The method of  claim 77 , further comprising: 
 insulating the second set of edges by oxidizing the working surface.    
   
   
       81 . The method of  claim 77 , further comprising: 
 insulating the second set of edges by nitriding the working surface.    
   
   
       82 . The method of  claim 77 , further comprising: 
 corrugating the working surface by exposing the working surface to an etchant that etches the first set of edges substantially faster than the second set of edges.    
   
   
       83 . The method of  claim 77 , further comprising: 
 corrugating the working surface by exposing the working surface to an etchant that etches the second set of edges substantially faster than the first set of edges.    
   
   
       84 . The method of  claim 77 , further comprising: 
 exposing the working surface to an etchant that etches the second set of edges substantially faster than the first set of edges; and    exposing the working surface to an anisotropic etchant that preferentially etches certain crystallographic planes of the conductive materials or the other materials.    
   
   
       85 . The method of  claim 77 , further comprising: 
 corrugating the working surface by exposing the working surface to a material that attaches preferentially to the first set of edges than to the second set of edges.    
   
   
       86 . The method of  claim 77 , further comprising: 
 corrugating the working surface by exposing the working surface to metals and/or conductive nanoparticles that attach preferentially to the first set of edges than to the second set of edges.