CYLINDRICAL GRAPHENE NANORIBBON ON METAL

Three-dimensional (3D) graphene nanoribbons and methods for fabricating 3D graphene nanoribbons that may readily function as solenoid windings and the like. In one embodiment, a method of fabricating a 3D graphene nanoribbon (100) may include coating a side surface (102A) of a 3D insert (102) with a metal (104) appropriate for graphene growth thereon. The method may also include growing a layer (106) of graphene directly on the metal coating. The method may also include removing a strip of the graphene layer and metal coating (106/104) to expose the side surface (102A) of the insert (102) while leaving a line (108) of graphene on metal winding around the insert (102) and extending continuously from a first end (108A) of the line (108) to a second end (108B) of the line (108).

FIELD OF THE INVENTION

The present invention relates generally to the fabrication of graphene nanoribbons (GNRs), and more particularly to three-dimensional (3D) GNRs and their fabrication.

BACKGROUND OF THE INVENTION

Graphene is generally understood to be a pure carbon substance that is an allotrope of carbon whose structure is a single planar sheet of sp2-bonded carbon atoms densely packed in a honeycomb crystal lattice structure. GNRs are ultra-thin lines of graphene. Since graphene exhibits properties such as high carrier mobility, GNRs have been considered for use in high-performance electronic devices such as, for example, as conductors for solenoid windings. Two-dimensional (2D) fabrication techniques where long GNRs are fabricated on flat surfaces are possible. However, in order to use long GNRs as solenoid windings or in other generally 3D applications, challenging lift-off techniques must be undertaken in order to remove 2D fabricated GNRs from the surfaces on which they are formed. Given their ultra-thin nature, breaks, cracks, or other discontinuities may readily occur during such lift-off processes.

SUMMARY OF THE INVENTION

Accordingly, 3D graphene nanoribbons and methods for fabricating 3D graphene nanoribbons that may readily be utilized in a variety of devices including, for example as solenoid windings and the like, are provided.

In one aspect, a method of fabricating a 3D graphene nanoribbon may include coating a side surface of a 3D insert with a metal appropriate for graphene growth thereon. The method may also include growing a layer of graphene directly on the metal coating. The method may also include removing a strip of the graphene layer and metal coating to expose the side surface of the insert while leaving a line of graphene on metal winding around the insert and extending continuously from a first end of the line to a second end of the line.

In another aspect, a 3D graphene nanoribbon may include a 3D insert having a side surface thereof coated with a metal appropriate for graphene growth thereon. The 3D graphene nanoribbon may also include a layer of graphene grown directly on the metal coating. The 3D graphene nanoribbon may also include a line of graphene on metal winding around the insert and extending continuously from a first end of the line to a second end of the line. The line may be formed by removing a strip of the graphene layer and metal coating to expose the side surface of the insert and leaving the graphene on metal line remaining on the side surface of the insert.

Various refinements exist of the features noted in relation to the various aspects of the present invention. Further features may also be incorporated in the various aspects of the present invention. These refinements and additional features may exist individually or in any combination, and various features of the various aspects may be combined. These and other aspects and advantages of the present invention will be apparent upon review of the following Detailed Description when taken in conjunction with the accompanying figures.

DETAILED DESCRIPTION

FIGS. 1A-1Bshow side perspective and end views of one embodiment of a three-dimensional (3D) graphene nanoribbon100. The 3D graphene nanoribbon100is formed on the side surface102A of an insert102having a circular or elliptical cross-section and a longitudinal axis102B. In this regard, the insert102may, for example, be a cylinder, a cone or the like. In other embodiments, it may be possible for the insert102to have differently a shaped cross-section such as, for example, triangular, rectangular, pentagonal, hexagonal, etc. The insert102may be comprised of a ceramic material (e.g., silicon). The insert102may be appropriately sized (e.g., in height and diameter), in order to accommodate formation of a sufficient number of windings thereon for the intended application of the 3D graphene nanoribbon100. As depicted inFIGS. 1A-1B, the insert102may be hollow. In other embodiments, the insert102may be solid.

The side surface102A of the insert102has a metallic coating104. A sputter coating process may be used to provide the metallic coating104on the side surface102A of the insert102. The metallic coating104comprises a metal appropriate for graphene growth thereon. In this regard, the metallic coating104may, for example, include metals such as copper, nickel or any other metal alloys appropriate for the growth of graphene thereon. A layer of graphene106is grown directly on the metal coating104.

A continuous strip of the metallic coating104and the graphene layer106grown thereon are removed from the insert102exposing a portion of the side surface102A of the insert100and leaving a continuous graphene on metal line108. The continuous graphene on metal line108may wind around the side surface102A of the insert102in a helical fashion from a first end108A of the graphene on metal line108proximal to one end of the insert100to a second end108B of the graphene on metal line108proximal to the opposing end of the insert102. The continuous graphene on metal line108may have a desired width110. In this regard, the desired width110may, for example, be 1.10 microns or less. There may also be a desired spacing112between adjacent windings. In this regard, the desired spacing may, for example, be about 2.00 microns or less. In some embodiments such as shown, the width110and/or spacing112may be consistent over the length of the graphene on metal line108. In other embodiments, the width110and/or spacing112may vary over the length of the graphene on metal line108.

A length of the insert102measured along its longitudinal axis102B may be selected depending upon how many windings of the graphene on metal line108are desired as well as the width110of the graphene on metal line108and the spacing112between adjacent windings of the graphene on metal line108. It should be noted that the figures are not drawn to scale, and, thus an actual 3D graphene nanoribbon100could have many more windings of the graphene on metal line108formed on the insert100than depicted.

Removal of the portion of the metallic coating104and the graphene layer106grown thereon may be accomplished in a variety of manners including, for example, by using an ablation tool. The ablation tool may be used to ablate the strip of the metallic coating104/graphene layer106that is to be removed leaving the continuous graphene on metal line108. In one embodiment, the ablation tool may comprise a laser.

FIG. 2shows the steps that may be included in one embodiment of a method200for fabricating a 3D graphene nanoribbon. In step210of the method200, a side surface of a 3D insert is coated with a metal appropriate for graphene growth thereon. The 3D insert may be comprised of ceramic material (e.g., silicon) and may have a circular or elliptical cross-section. In this regard, the 3D insert may be a cylindrically shaped insert or a conical shaped insert. In other embodiments, the 3D insert may also have different cross sections (e.g. triangular, rectangular, pentagonal, hexagonal, etc.). Step210may be accomplished by sputter coating the side surface of the insert with the metal. Various metals may be used to coat the side surface of the 3D insert including, for example copper, nickel and any other metal alloys appropriate for graphene growth thereon.

In step220, a layer of graphene is grown directly over the metal coating.

In step230, a strip of the graphene layer and metal coating is removed to expose the side surface of the insert. Removal of the strip leaves a line of graphene on metal winding around the insert in a helical fashion that extends continuously from a first end of the line to a second end of the line.

Step230may be accomplished in a variety of manners. In one embodiment, an ablation tool such as a laser may be used to remove the strip of the graphene layer and metal coating by directing a laser beam onto each portion of the strip for a sufficient amount of time to ablate (e.g., heat until the graphene and metal vaporize) the material being removed. Step230may involve one or more sub-steps to achieve the continuous graphene on metal line winding in a helical fashion around the side surface of the insert.

In sub-step232, the insert is rotated around a longitudinal axis of the insert while translating the insert relative to the ablation tool in the direction of the longitudinal axis.FIG. 3Aillustrates sub-step232, in which a laser250is used as the ablation tool. As indicated by arrow260, the insert102is rotated around the longitudinal axis102B of the insert102while also translating the insert102relative to the laser250in the direction of the longitudinal axis102B as indicated by arrow270. As the insert102is rotated and translated, the laser250directs a laser beam252onto the metal coating/graphene layer104/106on the side surface102A of the insert102. The laser beam252is focused to ablate the metal coating/graphene layer104/106in a strip as the insert102is rotated and translated leaving a non-ablated continuous line108of graphene on metal winding in a helical fashion around the insert102.

In sub-step234, the insert is rotated around a longitudinal axis of the insert while translating the ablation tool in the direction of the longitudinal axis relative to the insert.FIG. 3Billustrates sub-step234, in which a laser250is used as the ablation tool. As indicated by arrow260, the insert102is rotated around the longitudinal axis102B of the insert102while also translating the laser250relative to the insert102in the direction of the longitudinal axis102B as indicated by arrow270. As the insert102is rotated and laser250is translated, the laser250directs a laser beam252onto the metal coating/graphene layer104/106on the side surface102A of the insert102. The laser beam252is focused to ablate the metal coating/graphene layer104/106in a strip as the insert102is rotated and the laser250is translated leaving a non-ablated continuous line108of graphene on metal winding in a helical fashion around the insert102.

In sub-step236, the ablation tool is rotated around a longitudinal axis of the insert while translating the ablation tool in the direction of the longitudinal axis relative to the insert.FIG. 3Cillustrates sub-step236, in which a laser250is used as the ablation tool. As indicated by arrow260, the laser250is rotated around the longitudinal axis102B of the insert102while also translating the laser250relative to the insert102in the direction of the longitudinal axis102B as indicated by arrow270. As the laser250is rotated and translated, the laser250directs a laser beam252onto the metal coating/graphene layer104/106on the side surface102A of the insert102. The laser beam252is focused to ablate the metal coating/graphene layer104/106in a strip as the laser250is rotated and translated leaving a non-ablated continuous line108of graphene on metal winding in a helical fashion around the insert102.

In sub-step238, the laser is rotated around a longitudinal axis of the insert while translating the insert in the direction of the longitudinal axis relative to the laser. FIG. 3D illustrates sub-step238, in which a laser250is used as the ablation tool. As indicated by arrow260, the laser250is rotated around the longitudinal axis102B of the insert102while also translating the insert102relative to the laser250in the direction of the longitudinal axis102B as indicated by arrow270. As the laser250is rotated and the insert102is translated, the laser250directs a laser beam252onto the metal coating/graphene layer104/106on the side surface102A of the insert102. The laser beam252is focused to ablate the metal coating/graphene layer104/106in a strip as the laser102is rotated and the insert102is translated leaving a non-ablated continuous line108of graphene on metal winding in a helical fashion around the insert102.

Additionally, the foregoing description has been presented for purposes of illustration and description and is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings may be possible. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.