Patent Application
20140342236
1. Field of the Invention
The invention relates generally to ordered, nanoarrays, and more specifically to ordered, one-dimensional and three-dimensional nanoarrays comprising conductive materials, and more specifically for use as battery electrodes.
2. Description of the Related Art
Ordered one-dimensional (1) and three-dimensional (3D) nanoarrays are required for advanced solar cell concepts and battery architectures among other applications. A scalable method is needed to achieve ordered 1D and 3D nanoarrays. Some applications would also benefit if the 1D and 3D nanoarray array included nanorods that were single-crystal in nature. Other applications would benefit if all of the nanorods that make up the nanoarray had the same orientation.
While fabrication of a variety of interesting nanostructures has been demonstrated in small samples, a predominant number of the methods for making such nanostructures are not readily scalable or completely reproducible. In many cases, for example, deposits in a furnace downstream trap have to be scraped and nanostructures harvested therefrom. Therefore, such nanostructures are prohibitively expensive and the utility thereof cannot be realized. Reproducible and controlled fabrication of nanostructures is needed for many novel electronic and electromagnetic devices such as those involving semiconductors and superconductors.
Various embodiments relate to an article having a substrate surface, such as a biaxially-textured substrate surface and a plurality of vertically-aligned, epitaxial nanopillars supported on the surface substrate. The nanopillars can include a coating layer or layers which can be electronically active.
According to certain embodiments, arrays of ordered, regularly-placed, 1D nanorods of metals/alloys can be formed by a scalable method. The 1D nanorods can be single-crystal-like when formed on a biaxially-textured substrate. Various embodiments meet the need for ordered one dimensional nanoarrays for applications such as advanced solar cell, battery architectures, electronic devices, and other applications. Various embodiments provide a scalable method for producing ordered 1D nanoarrays. Various embodiments provide a 1D nanoarray array including nanorads that are single-crystal in nature. Still other embodiments provide nanoarrays wherein all of the nanorods that make up the nanoarray have the same orientation.
Various embodiments relate to an article, particularly a battery electrode, that includes a biaxially-textured substrate and a plurality of vertically-aligned nanopillars disposed on a surface of the substrate. The biaxially-textured substrate can include a first conductive material. The plurality of nanopillars can include a second conductive material. The first conductive material can be selected from the group consisting of copper, nickel, aluminum, iron, silver and their alloys thereof, and combinations thereof. The plurality of nanopillars can be epitaxial. One or more of the plurality of nanopillars can be biaxially textured. One or more of the plurality of nanopillars can be {100}<100>. One or more of the plurality of nanopillars can be self-assembled with regular nanoscale spacings. One or more of the plurality of nanopillars can have a diameter in the range of 1-200 nm. The second conductive material can be selected from the group consisting of copper, nickel, aluminum, iron, silver and their alloys thereof, and combinations thereof. The surface of the substrate can be biaxially textured. The surface of the substrate can be {100}<100>.
According to various embodiments, the article, particularly the battery electrode, can further include a plurality of nanobranches supported by the nanopillars. The plurality of nanobranches can be horizontally-aligned, epitaxial, and can include a third conductive material. The nanobranches can be epitaxial with respect to the nanopillars upon which they are supported, for example. The third conductive material can be selected from the group consisting of copper, nickel, aluminum, iron, silver and their alloys thereof, and combinations thereof. One or more of the plurality of nanobranches can have a diameter in the range of 1-200 nm. One or more of the plurality of nanobranches can be single-crystal-like. One or more of the plurality of nanobranches can be cube-textured. One or more of the plurality of nanobranches can be self-assembled with regular nanoscale spacings.
Various embodiments relate to a method of making an article, particularly a battery electrode. The method can include providing a substrate that comprises a first metallic material; depositing a first layer of a metallic material onto the substrate; anodically oxidizing the first layer to form a first self-assembled nanostructure defining a first plurality of nano-hole columns; filling the first plurality of nano-hole columns with a third metallic material to form a first plurality of nanopillars; and removing the first self-assembled nanostructure to leave the first plurality of nanopillars supported on the surface of the substrate. Removing the first self-assembled nanostructure can include one selected from chemical etching, plasma etching, reverse sputtering, ion-bombardment, and combinations thereof. The surface of the substrate can be biaxially-textured, or cube-textured. The method can further include immersing the first plurality of nanopillars in an electrode material. The electrode material can be, for example, silicon. According to some particularly preferred embodiments, the first metallic material is copper or an alloy thereof. The first metallic material can be single-crystal-like. The second metallic material can be a metal that upon anodization forms an ordered array of nanohole columns through the first layer. According to some particularly preferred embodiments, the second metallic material is selected from aluminum and titanium. According to some particularly preferred embodiments, the third metallic material is copper or an alloy thereof. The third metallic material can be single-crystal-like. The third metallic material can be electrodeposited to fill the first plurality of hollow nanopillars. The first plurality of nano-hole columns can be arranged in a hexagonal, self-assembled pattern. The first plurality of nano-hole columns be defined by and/or can comprise alumina, which can be formed upon the anodization of the first layer, for example. Each of the first plurality of nano-hole columns can have a length of from 1 nm to 1 mm and a diameter of 1 nm to 100 nm. The first plurality of nanopillars can be vertically-aligned with respect to the surface of the substrate. The first plurality of nanopillars can be epitaxial with respect to the surface of the substrate.
According to various embodiments, the method of making an article, particularly a battery electrode, can further include depositing a resist layer on the substrate at interstices between the first plurality of nanopillars; depositing a second layer comprising a fourth metallic material on the resist and the first plurality of nanopillars; anodically oxidizing the second layer to form a second self-assembled nanostructure comprised of a second plurality of nano-hole columns, wherein the second plurality of nano-hole columns are perpendicular to the first plurality of nanopillars; filling the second plurality of nano-hole columns with a fifth metallic material to form a second plurality of nanopillars; and removing the second self-assembled nanostructure to leave the second plurality of nanopillars supported by the first plurality of nanopillars. Removing the second self-assembled nanostructure can include one selected from chemical etching, plasma etching, reverse sputtering, ion-bombardment, and combinations thereof. The second plurality of nanopillars can interconnect with the first plurality of nanopillars to form a nanofence. The method can further include immersing the first plurality of nanopillars in an electrode material. The electrode material can be, for example, silicon. The fourth metallic material can be aluminum. The fifth metallic material can be copper or an alloy thereof. The second self-assembled nanostructure can include alumina. The second plurality nano-hole columns can be arranged in a hexagonal, self-assembled pattern. The fifth metallic material can be electrodeposited to fill the second plurality of hollow nanopillars. The second plurality of nanopillars can be horizontally-aligned with respect to the surface of the substrate. The second plurality of nanopillars can be epitaxial. The resist layer can have a thickness of from a 1 nm to 100 nm.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims, and accompanying drawings where:
It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.
The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention as well as to the examples included therein. All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may include numbers that are rounded to the nearest significant figure.
As used herein, a first layer is “supported on” second layer if the first layer is above the second layer in a stack, whereas a first layer is “deposited on” a second layer if the first layer is above and in direct contact with the second layer. In other words, there can be intermediate layers between a first layer supported on a second layer, whereas there are no intermediate layers if the first layer is deposited on the second layer. It is intended that where the phrase “supported on” is used in the specification, the layer can be either supported on or deposited on the layer by which it is supported.
As used herein, “epitaxy” refers to the deposition of a crystalline overlayer on a substrate, where there is registry between the overlayer and the substrate. The overlayer is called an “epitaxial” film or “epitaxial” layer. Epitaxial films may be grown from gaseous or liquid precursors. Because the substrate acts as a seed crystal, the deposited film may lock into one or more crystallographic orientations with respect to the substrate crystal. If the overlayer either forms a random orientation with respect to the substrate or does not form an ordered overlayer, it is termed non-epitaxial growth. If an epitaxial film is deposited on a substrate of the same composition, the process is called homoepitaxy; otherwise it is called heteroepitaxy. Homoepitaxy is a kind of epitaxy performed with only one material, in which a crystalline film is grown on a substrate or film of the same material. Heteroepitaxy is a kind of epitaxy performed with materials that are different from each other. In heteroepitaxy, a crystalline film grows on a crystalline substrate or film of a different material. Heterotopotaxy is a process similar to heteroepitaxy except that thin film growth is not limited to two-dimensional growth; the substrate is similar only in structure to the thin-film material.
As used herein, “non-epitaxial” refers to the deposition of a overlayer on a substrate, wherein there is no registry between the overlayer and the substrate.
As used herein, “registry” between an overlayer and a substrate means that there is a crystallographic orientational relationship between the atoms in the substrate and the overlayer.
Atomic arrangements in crystalline solids can be described by referring the atoms to the points of intersection of a network of lines in three dimensions. Such a network is called a “space lattice” and can be described as an infinite three-dimensional array of points. In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals.
A lattice system is a class of lattices with the same point group. In three dimensions there are seven lattice systems: triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal, and cubic. The lattice system of a crystal or space group is determined by its lattice but not always by its point group.
Crystal systems are a modification of the lattice systems to make them compatible with the classification according to point groups. They differ from crystal families in that the hexagonal crystal family is split into two subsets, called the trigonal and hexagonal crystal systems. Two point groups are placed in the same crystal system if the sets of possible lattice systems of their space groups are the same. A cubic crystal system comprises three equal axes at right angles and includes three space lattices: simple cubic, body-centered cubic, and face-centered cubic. A tetragonal crystal system comprises three axes at right angles, two of which are equal and includes two space lattices: simple tetragonal and body-centered tetragonal. An orthorhombic crystal system comprises three unequal axes at right angles and includes four space lattices: simple orthorhombic, body-centered orthorhombic, base-centered orthorhombic, and face-centered orthorhombic. A rhombohedral crystal system comprises three equal axes, equally inclined and includes one space lattice: simple rhombohedral. A hexagonal crystal system comprises two equal axes at 120 degrees and a third axis at right angles and includes one space lattice: simple hexagonal. A monoclinic crystal system comprises three unequal axes where one pair are not at right angles and includes two space lattices: simple monoclinic and base-centered monoclinic. A triclinic crystal system comprises three unequal axes that are unequally inclined and not at right angles, and includes one space lattice: simple triclinic.
A crystal family comprises point groups and is formed by combining crystal systems whenever two crystal systems have space groups with the same lattice. In three dimensions a crystal family is almost the same as a crystal system (or lattice system), except that the hexagonal and trigonal crystal systems are combined into one hexagonal family. In three dimensions there are six crystal families: triclinic, monoclinic, orthorhombic, tetragonal, hexagonal, and cubic. The crystal family of a crystal or space group is determined by either its point group or its lattice, and crystal families are the smallest collections of point groups with this property.
As used herein, “crystallographic orientation” refers to the particular crystal system to which a material belongs.
As used herein, “flexible” means capable of bending easily without breaking.
As used herein, “biaxially-textured” refers to two crystallographic axes being aligned. For example, the term “biaxially-textured” can refer to the {100}<100> crystallographic orientation in a substrate, which means that the (100) plane is aligned parallel to the flat plane of the substrate and the [100] direction is aligned along the long axis of the substrate or the rolling direction of the substrate. The degree of biaxial texture in a biaxially-textured surface, as specified by the FWHM of the out-of-plane and in-plane diffraction peak, can be within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9, 15, 15.1, 15.2, 15.3, 15.4, 15.5, 15.6, 15.7, 15.8, 15.9, 16, 16.1, 16.2, 16.3, 16.4, 16.5, 16.6, 16.7, 16.8, 16.9, 17, 17.1, 17.2, 17.3, 17.4, 17.5, 17.6, 17.7, 17.8, 17.9, 18, 18.1, 18.2, 18.3, 18.4, 18.5, 18.6, 18.7, 18.8, 18.9, 19, 19.1, 19.2, 19.3, 19.4, 19.5, 19.6, 19.7, 19.8, 19.9, and 20 degrees. For example, according to certain preferred embodiments, the degree of biaxial texture in a biaxially-textured surface, as specified by the FWHM of the out-of-plane and in-plane diffraction peak, can be greater than 2 degrees and less than 20 degrees, preferably less than 15 degrees, and optimally less than 10 degrees. As will be understood the composition of the materials described herein can vary greatly depending on the particular application. The biaxially-textured surface can be the surface of any biaxially textured substrate including one or more layers. Examples of suitable materials for the substrate include, but are not limited to, a single crystal substrate; a biaxially textured substrate; and an untextured substrate having adhered thereon a biaxially-textured crystallographic surface, such as an ion-beam assisted deposition (IBAD) substrate.
As used herein, “vertically-aligned” features are aligned substantially normal to a surface. Vertically-aligned features can deviate from normal with respect to a surface by an angle within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9, and 15 degrees. For example, according to certain preferred embodiments, vertically-aligned features can deviate from normal with respect to a surface by an angle of less than 15 degrees, or less than 10 degrees, or less than 5 degrees, or less than 1 degree, or less than 0.1 degrees.
As used herein, “horizontally-aligned” features are aligned substantially parallel to a surface. Vertically-aligned features can deviate from parallel with respect to a surface by an angle within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9, and 15 degrees. For example, according to certain preferred embodiments, horizontally-aligned features can deviate from parallel with respect to a surface by an angle of less than 15 degrees, or less than 10 degrees, or less than 5 degrees, or less than 1 degree, or less than 0.1 degrees. As used herein, “nanoscale” refers to a size measurable in nanometers or microns. The term “nanoscale” can include a size within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, and 1000 nanometers. For example, according to certain preferred embodiments, the term “nanoscale” includes a size of from 1 to 100 nanometers.
As used herein, “nanopillar” refers to a substantially cylindrical column, rod, or tube having at least one nanoscale dimension. The at least one nanoscale dimension can be an outer diameter, an inner diameter (in the case of a tube), and/or a length as measured from a substrate upon which the nanopillar is deposited to an outer extremity of the nanopillar. The term “nanopillar” encompasses the terms “nanorod” and “nanotube.” The term “substantially cylindrical” means generally having the shape of a cylinder and includes objects and structures that deviate from the precise geometric concept of a cylinder. As used herein, “nanorod” refers to a solid nanopillar. A nanorod can be formed of formed of one or more compositions. For example, a nanorod can be formed of a single, uniform composition. As used herein, “nanotube” refers to a hollow nanopillar. A nanotube can be, but is not necessarily filled with a core phase. Nanopillars can have at least one dimension ranging from 1 to 500 nm, or 5 to 250 nm, or 10 to 100 nm, or any combination of these endpoints, e.g., 250 to 500 nm. Nanopillars generally have at least one dimension that is less than 100 nm. An outer diameter of the vertically-aligned, epitaxial nanopillars can range from 1 to 100 nm, or from 2 to 75 nm, or from 5 to 50 nm, or any combination of these endpoints, e.g., 2 to 50 nm. An inner diameter of nanotubes can range from 1 to 50 nm, or from 2 to 40 nm, or from 3 to 30 nm, or any combination of these endpoints, e.g., 2 to 3 nm. As used herein, “nanofence” refers to a three-dimensional, grid-like structure having interconnected branches extending in one or more directions.
As used herein, “array” refers to a systematic or random arrangement of objects, usually in rows and columns. For example, a nanopillar array comprises a plurality of nanopillars arranged in a systematic grouping, which can include one or more rows and/or one or more columns of nanopillars.
As used herein, “ordered array” refers to a systematic arrangement of objects, usually in rows and columns.
As used herein, “regular nanoscale spacings” can refer to distances between immediately adjacent nanopillars in a nanopillar array. Two nanopillars are immediately adjacent, if they are in the vicinity of each other and if no third nanopillar is positioned between them. The distances between immediately adjacent nanopillars can be on a nanoscale as defined herein. The distances are “regular” if the magnitude of each distance deviates from an average of all distances between immediately adjacent nanopillars by a percentage within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9, and 15 percent. For example, according to certain preferred embodiments, the distances are “regular” if the magnitude of each distance deviates from an average of all distances between immediately adjacent nanopillars by a percentage within a range of from 0 to 10 percent.
As used herein, “nano-hole column” refers to a nanoscale void in a surface or layer. According to various embodiments, a plurality of nano-hole columns can be formed in a surface or layer via anodic oxidization. The plurality of nano-hole columns can form a self-assembled array or pattern of nanoscale holes or voids in the surface or layer. The plurality of nano-hole columns can have a regularly-occurring shape, such as, but not limited to a hexagonal shape.
As used herein, “sub-pillars” refers to a subpart of a nanopillar having a different composition than another sub-pillar forming part of the same nanopillar. In other words, a nanopillar includes subpillars, if it has segments with different compositions along its length. The sub-pillars can be stacked on one another. Nanopillars formed from sub-pillars can be used to replace any of the nanopillars described herein. For example, sub-pillar-based nanopillars can be coated; can be surrounded by a matrix phase, or both. In addition, each of the sub-pillars can be coated with a sub-coating and can be immersed by a matrix phase.
As used herein, “nanopattern” refers to a nanoscale arrangement of features. The arrangement can be ordered or random.
As used herein, “metallic” or “metallic material” refers to a composition including but not limited to aluminum, antimony, arsenic, barium, beryllium, bismuth, boron, cadmium, cesium, chromium, cobalt, copper, gallium, germanium, gold, hafnium, indium, iron, lead, lithium, manganese, mercury, molybdenum, nickel, platinum, palladium, rhodium, iridium, osmium, ruthenium, rhenium, rubidium, scandium, selenium, silver, strontium, tantalum, tellurium, thallium, thorium, tin, titanium, tungsten, vanadium, zinc, zirconium, alloys, and combinations thereof.
As used herein, “conductive” or “conductive material” refers to any conductive material, including but not limited to a metallic material.
As used herein, “photovoltaic material” refers to a material including but not limited to single-crystal silicon, polycrystalline silicon, gallium arsenide, amorphous silicon, cadmium telluride, copper indium diselenide, and combinations thereof.
As used herein, “electrical storage material” refers to a material including but not limited to graphene, and solar energy storage materials described in U.S. Pat. No. 4,497,724 which is hereby incorporated by reference in its entirety.
As used herein, “catalyst” refers to a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. As used herein, “nanocatalyst” refers to a nanoscale catalyst. A variety of nanocatalysts can be used in accordance with the various embodiments including various metallic materials.
As used herein, “nanocatalyst pattern” refers to an arrangement of nanocatalysts. The arrangement can be ordered or random.
As used herein, “anodization” is an electrolytic process used to form an oxide layer on the surface of metal parts.
As used herein, “anodization catalyst layer” refers to a layer deposited on a surface which will be subsequently anodized. The anodization catalyst layer can include a metallic material.
As used herein, “single-crystal” refers to a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries.
As used herein, “single-crystal-like” refers to a material which has an orientation almost like that of a single-crystal but is polycrystalline.
As used herein, “1D” or “one-dimensional” refers to nanopillars that extend predominantly in a single axial direction relative to a surface upon which they are deposited. One dimensional nanopillars have dimensions in three axial directions, but their predominant dimension is in a single direction, e.g. vertical.
As used herein, “3D” or “three-dimensional” refers to nanopillars that extend in three axial directions relative to a surface upon which they are deposited. A three-dimensional nanopillar can be branched.
As used herein, “branch” refers to a portion of a three-dimensional nanopillar extending along an axis that is substantially parallel to a surface upon which the nanopillar is deposited. As used herein, “branched” refers to nanopillar having one or more braches, e.g. a three-dimensional nanopillar. The branches of a three-dimensional nanopillar can be connected or unconnected. As used herein, “unbranched” refers to a nanopillar without branches.
As used herein, “resist” refers to a thin layer used to transfer a circuit pattern to the semiconductor substrate which it is deposited upon. A resist can be patterned via lithography to form a (sub)micrometer-scale, temporary mask that protects selected areas of the underlying substrate during subsequent processing steps. The material used to prepare said thin layer is typically a viscous solution. Resists are generally proprietary mixtures of a polymer or its precursor and other small molecules (e.g. photoacid generators) that have been specially formulated for a given lithography technology. Resists used during photolithography are called photoresists.
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The matrix phase 24 can be continuous, while the vertically-aligned nanopillars can be spatially separated in an ordered array. The matrix phase 24 can be amorphous or crystalline depending on the particular function of the article 10 and the electronically active layer 22. The matrix phase 24 can be any material useful in an article 10 having a substrate 12 with a biaxially textured surface 14, including, but not limited to a photovoltaic material or an electrical storage material.
The nanopillar(s) 16 coated with the coating 28 can optionally be immersed in a matrix phase 24, as shown in any of
The coating 28 can have a first composition and the matrix phase 24 can have a second composition. The first and second compositions can be the same or different.
The coating 28 can have a first crystallographic orientation and the matrix phase 24 can have a second crystallographic orientation. The first and second crystallographic orientations can be the same or different. The first crystallographic orientation can be the same as the crystallographic orientation of the nanopillars 16 and the second crystallographic orientation can be the same as that of the biaxially-textured surface 14. The {100] orientation, being particularly preferred.
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A template precursor layer 40 can be deposited on the anodization catalyst layer 46. In embodiments where the anodization catalyst layer 46 is not present, the precursor layer 40 can be deposited directly onto the biaxially-textured surface 14 of the substrate 12. According to other embodiments, the anodization catalyst layer 46 can be supported on the biaxially textured surface 14 and the template precursor layer 40 can be supported on the anodization catalyst layer 46. Exemplary materials for the template precursor layer 40 include metallic materials. According to certain preferred embodiments, the template precursor layer 40 can be copper, titanium, magnesium, zinc, niobium, tantalum, aluminum and alloys thereof. According to certain particularly preferred embodiments, the template precursor layer 40 can include copper and/or copper alloys.
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In some instances, after formation of the template 36, debris may be left behind to cover the biaxially-textured surface 14 of the substrate 12. The debris can include, but is not limited to anodized or unanodized portions of the anodization catalyst layer 46, and/or anodized or unanodized portions of the template 36. In such instances, it may be necessary to remove the debris prior to growing the nanotubes 20. In addition to debris, films and layers can form during the process steps. One approach for removing such films, layers or debris, including using an etchant. The etchant can include one or more selected from one of many standard etchants including but not limited to copper(II) chloride, copper(II) sulfate, hydrochloric acid, nitric acid, hydrofluoric acid, potassium ferricyanide, potassium hydroxide, picric acid, and combinations thereof.
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A method is also disclosed for producing nanopillars 16 that include a plurality of sub-pillars 32, as shown in
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(1) In-Situ Deposition: In this case, the film is deposited epitaxially on the biaxially textured surface 14 over, around and throughout the plurality of nanopillars 16 using an in-situ deposition technique including, but not limited to, laser ablation, sputtering, e-beam co-evaporation, chemical vapor deposition, metal-organic chemical vapor deposition, chemical solution deposition, liquid phase epitaxy, hybrid liquid phase epitaxy, and the like. The result is an epitaxial matrix phase 24 deposited on the biaxially textured surface 14 between the nanopillars 16.
(2) Ex-Situ Deposition: In this case, first a precursor film is deposited on the biaxially textured surface 14 over, around and throughout the plurality of nanopillars 16. This is followed by a heat-treatment or an annealing step at a temperature greater than 500° C. to form an epitaxial matrix phase 24, e.g., a superconductor matrix phase, within which the nanopillars 16 are embedded. Examples of techniques for this step include, but are not limited to, chemical solution deposition methods, such as using metal-organic deposition (MOD) techniques, particularly with fluorine-containing precursors or e-beam or thermal co-evaporation with fluorine-containing precursors.
With respect to any embodiment described herein, the matrix phase 24, nanopillars 16, coatings 28 and core phase 30 can be any material useful in an article 10 having a substrate 12 with a biaxially textured surface 14, including, but not limited to a metallic material, a photovoltaic material, an electrical storage material, and combinations thereof.
Exemplary compositions for the matrix phase 24, nanopillars 16, coatings 28 and core phase 30 include, but are not limited to, metallic materials, oxides, nitrides, borides, carbides and combinations thereof. Where the composition of the matrix phase 24, nanopillars 16, coatings 28 and/or core phase 30 is not amorphous, the compositions can have a variety of crystal structures, which independently include, but are not limited to, rock-salt, fluorite, perovskite, double-perovskite and pyrochlore. The nanopillars 16, coatings 28 and/or core phase 30 can be formed using any technique useful for applying thin films, whether epitaxial or not, including, but not limited to, laser ablation, sputtering, e-beam co-evaporation, chemical vapor deposition, metal-organic chemical vapor deposition, chemical solution deposition, liquid phase epitaxy, hybrid liquid phase epitaxy, chemical solution deposition methods, such as using metal-organic deposition (MOD) techniques, and the like. Of course, the composition and deposition technique of the matrix phase 24, nanopillars 16, coatings 28 and core phase 30, will depend on the particular application in which the article 10 is used.
Anodic oxidation of an epitaxial Al layer may result in a pore structure which is different from that shown in
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As used herein, the nanopillars are equidistant if the difference between the distance between two adjacent nanopillars are within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9, and 15 percent. For example, nanopillars are “equidistant” if the difference between the distance between two adjacent nanopillars is less than 15%, less than 10%, or less than 5%, or less than 1% different than the distance between other adjacent nanopillars in the row or column.
The rows or columns in these arrays include a number of nanopillars where each nanopillar in the row or column is equidistant from each adjacent nanopillar. The number of nanopillars in the rows or columns can be within a range having a lower limit and/or an upper limit. The range can include or exclude the lower limit and/or the upper limit. The lower limit and/or upper limit can be selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, and 50. For example, according to certain preferred embodiments, the number of nanopillars in the rows or columns can be at least 5 nanopillars, at least 10 nanopillars, at least 20 nanopillars, or at least 50 nanopillars.
Other preferred embodiments can provide a scalable method to form single-crystal-like, three-dimensional nanorods of metals/alloys such as copper (Cu) for battery electrodes or for solar cell collectors. Such preferred embodiments can include providing a biaxially-textured Cu foil or a biaxially-textured metal foil substrate; depositing aluminum (Al) onto the substrate, anodically oxidizing the Al layer to form a self-assembled nanostructure comprising nano-hole columns arranged in a hexagonal, self-assembled pattern. The nano-hole columns can comprise alumina (Al2O3). Next, according to certain preferred embodiments, copper (Cu) can be electrodeposited to form Cu nanorods. Since the Cu is electrodeposited onto a biaxially-textured surface, the Cu can grow epitaxially. The nanocolumns can be chemically etched away to leave a Cu foil having ordered, regularly placed single-crystal-like Cu nanorods.
The present invention has broad applicability for energy conversion as well as in areas of nanoelectronics such as ultra-high density magnetic storage and in nanostructured battery electrodes. Epitaxial nanorod arrays of materials with scintillation properties may be used for fabrication of advanced gamma-ray detectors.
Applications for the articles and methods described herein include dye-sensitized cells (DSC's) and hybrid organic-inorganic cells, which are widely considered as promising candidates for inexpensive, large-scale solar energy conversion. Prior art DSC's consist of a thick nanoparticle film that provides a large surface area for adsorption of light. Device efficiencies for such DSC's are limited by the trap-limited limited diffusion for electron transport, which is a slow process. It is believed that use of a nanopillar morphology would increase efficiency by accelerating electron transport and preventing recombination of electron-hole pairs.
The use of vertically-oriented, single crystal nanopillars of TiO2, SnO or ZnO will result in significant enhancement in electron transport. Coating the aligned nanorods with an oxide such as MgO can reduce carrier recombination because the coating may serve as an additional energy barrier, as a tunneling barrier and/or a passivate recombination center. In similar prior art materials, the nanorods are not perfectly aligned, consist of polycrystalline percolation networks, or both.
The epitaxial layers described herein, e.g., nanopillars, matrix phase, coating and core phase, can be deposited by a range of deposition techniques including e-beam evaporation, sputtering, chemical and physical vapor deposition techniques, pulsed laser ablation, chemical solution processing, and electrodeposition techniques as described in U.S. Pat. No. 6,670,308, which is hereby incorporated by reference in its entirety.
Exemplary templates can be formed using a single crystal aluminum sheet (i.e., template precursor), followed by anodic oxidation to form a self-organized nanopore array in the resulting anodized aluminum oxide (AAO) layer (i.e., template). In a particular example, the template can be formed on the biaxially textured surface by depositing a layer of aluminum (Al) on the cap or top buffer layer of a single crystal-like substrate (e.g., a fully buffered RABiTS substrate with three epitaxial oxide buffers), followed by complete anodic oxidation of the aluminum layer.
Once the epitaxial nanorod array has been deposited, the Al2O3 template can be chemically etched away if needed and, if needed, a matrix phase deposited between the epitaxial, single-crystal-like nanopillar array. For the ultra-high density recording media application, nanopillars comprising interconnected sub-pillars of different materials such as Co and Pd, will be epitaxially deposited successively using either physical vapor deposition or electrodeposition.
Moreover, various embodiments can be broadened, for example, by using an alternative to the AAO-type template to produce a nanocatalyst pattern. Laser interference lithography can be used to quickly produce a template pattern in nanoscale and in large areas.
Moreover, it is contemplated that growth of periodic nanostructures in two directions—vertical nanopillars and transverse nanopillars—can be achieved by supplying the catalyst for growth during deposition. For example, simultaneously depositing an oxide material with a metal catalyst such as MgO+Ni growth by PLD.
Sub-pillars 32 can be formed using iterative variations of the methods shown in
An alternate approach for forming sub-pillars 32 is to repeat the entire process shown in
One embodiment provides a scalable method to form arrays of one dimensional (1D) nanorods comprising metals and/or alloys, including but not limited to Cu. The 1D nanoarrays can be useful for battery electrodes, for solar cell collectors, and for various other electronic applications. The method can be performed in a roll-to-roll configuration.
The method can also be used to produce ordered nanorods comprising an oxide, a nitride, and or a carbide. According to such embodiments, the foil with metal/alloy nanorods is subsequently oxidized, nitride or carburized to transform the metallic portions into the desired oxide, nitride or carbide.
Various embodiments provide a scalable method to form one dimensional (1D) nanorods of metals/alloys such as Cu for battery electrodes or for solar cell collectors. Preferred embodiments of such methods can include providing a Cu foil or a metal foil substrate; depositing aluminum (Al) onto the substrate, anodically oxidizing the Al layer to form a self-assembled nanostructure comprising nano-hole columns arranged in a hexagonal, self-assembled pattern. The nano-hole columns can comprise alumina (Al2O3). Next, according to certain preferred embodiments, copper (Cu) can be electrodeposited to form Cu nanorods. The Al2O3 can then be chemically etched away to leave a Cu foil having ordered, regularly placed Cu nanorods. The chemical etching can be performed using an etchant. The etchant can include one or more selected from a list of standard etchants including but not limited to copper(II) chloride, copper(II) sulfate, hydrochloric acid, nitric acid, hydrofluoric acid, potassium ferricyanide, potassium hydroxide, picric acid, and combinations thereof.
Other preferred embodiments can provide a scalable method to form single-crystal-like, 1D nanorods of metals/alloys such as Cu for battery electrodes or for solar cell collectors. Such preferred embodiments can include providing a biaxially-textured Cu foil or a biaxially-textured metal foil substrate; depositing aluminum (Al) onto the substrate, anodically oxidizing the Al layer to form a self-assembled nanostructure comprising nano-hole columns arranged in a hexagonal, self-assembled pattern. The nano-hole columns can comprise alumina (Al2O3). Next, according to certain preferred embodiments, copper (Cu) can be electrodeposited to form Cu nanorods. Since the Cu is electrodeposited onto a biaxially-textured surface, the Cu can grow epitaxially. The Al2O3 can be chemically etched away to leave a Cu foil having ordered, regularly placed single-crystal-like Cu nanorods.
Either of these preferred embodiments can be further processed to provide three dimensional (3D) nanofences comprising conductive materials. U.S. Pat. No. 8,518,526, issued Aug. 27, 2013, filed Feb. 24, 2010, claiming priority to U.S. Provisional Patent Application No. 61/231,063, and entitled Structures with Three Dimensional Nanofences Comprising Single Crystal Segments is hereby incorporated by reference in its entirety. U.S. Pat. No. 8,518,526 describes an article including a substrate having a surface, and a nanofence supported by the surface. The nanofence includes a multiplicity of primary nanorods and branch nanorods. The primary nanorods are attached to the substrate and the branch nanorods are attached to at least one other of the primary nanorods and the branch nanorods. The primary nanorods and the branch nanorods are arranged in a three-dimensional, interconnected, interpenetrating, grid-like network defining interstices within the nanofence.
The preferred embodiments described above can be further processed by depositing a thin layer of a resist on a flat portion of the substrate where there are no nanorods. The resist can be selected from a list of standard resists used in the lithographic and semiconductor industry. Resists are generally proprietary mixtures of a polymer or its precursor and other small molecules (e.g. photoacid generators) that have been specially formulated for a given lithography technology. Those of ordinary skill in the art will be able to select a suitable resist material without undue experimentation.
An aluminum (Al) layer can be deposited on top of the resist and around the surface of the nanorods. The Al layer can be anodically oxidized to form a self-assembled nanostructure comprising nano-hole columns arranged in a hexagonal, self-assembled pattern. The nano-hole columns can comprise alumina (Al2O3). Copper (Cu) can then be electrodeposited to form Cu nanorods. Finally, the nano-hole columns can be chemically etched to remove the Al2O3, leaving a Cu foil having ordered, regularly placed Cu nanofence with nanorods in two perpendicular directions—perpendicular to the Cu foil and parallel to it.
It should be noted that any of the characteristics of the above-described embodiments can be applied to the embodiments described in
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The various embodiments described herein, can be extended to alloy nanorods and the metal substrate can be an alloy or anything conducting. The method can be done in a high-speed, reel-to-reel configuration. The method can also result in ordered, oxide or nitride or carbide nanorods, for example, if the foil with metal/alloy nanorods is subsequently oxidized, nitride or carburized. According to various embodiments, having a biaxially-textured, single-crystal-like metallic (e.g. copper) foil, makes the metallic (e.g. aluminum) layer aligned or epitaxial. The nanohole columns formed in the aluminum layer are all aligned then too. The metal nanorods formed upon filing of holes are also fully aligned and can grow epitaxially on the single-crystal-like substrate.
Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. The articles described herein can be formed using a variety of different methods consistent with the descriptions provided herein. However, it is to be understood that the methods described herein are exemplary and that there may exist variations that would also produce the articles disclosed herein.
All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C §112, sixth paragraph. In particular, the use of “step of” in the claims herein is not intended to invoke the provisions of 35 U.S.C §112, sixth paragraph.
This application is a Continuation-in-Part of U.S. patent application Ser. No. 12/849,970, filed Aug. 4, 2010, titled Vertically-Aligned Nanopillar Array on Flexible, Biaxially-Textured Substrates for Nanoelectronics and Energy Conversion Applications, which claimed priority to U.S. Provisional Application No. 61/231,501, filed Aug. 5, 2009, claimed priority to U.S. Provisional Application No. 61/231,063, filed Aug. 4, 2009, and was a continuation-in-part of U.S. application Ser. No. 12/711,309, entitled “Structures with Three Dimensional Nanofences Comprising Single Crystal Segments,” filed Feb. 24, 2010, the entireties of which are incorporated herein by reference.
The United States Government has rights in this invention pursuant to contract no. DE-AC05-00OR22725 between the United States Department of Energy and UT-Battelle, LLC.
| Number | Date | Country | |
|---|---|---|---|
| 61231501 | Aug 2009 | US | |
| 61231063 | Aug 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12849970 | Aug 2010 | US |
| Child | 14448625 | US | |
| Parent | 12711309 | Feb 2010 | US |
| Child | 12849970 | US |
