The present invention relates to a method for manufacturing a nanostructure in-situ at a predetermined point on a supporting carrier, and also to such a nanostructure device. In addition, the invention relates to electronics devices comprising a nanostructure made according to the method of the invention.
Nanostructures, for example in the shape of tubes, so called nanotubes, are structures which offer a number of new and interesting functionalities in, for example, the field of electronics. At present, however, there are difficulties associated with the manufacturing of nanostructures. Nanotubes, for example, are at present produced by means of a variety of procedures, which all have the common drawback that the nanotubes produced in these ways need a significant amount of postprocessing, and also need additional manipulation in order to be incorporated into devices.
The purpose of the invention is thus to solve the mentioned drawbacks of contemporary nanostructure technology, with a nonexclusive emphasis on nanotubes.
This purpose is achieved by a method for manufacturing a nanostructure in-situ at at least one predetermined point on a supporting carrier, which method comprises the steps of choosing a suitable material for a substrate to be comprised in the carrier, creating said substrate, and preparing a template on the substrate, wherein the template covers said predetermined point. The template is given a proper shape according to the desired shape of the final nanostructure, and a film of nanosource material with desired thickness, width and length is caused to be formed on the template. At least a part of the film of nanosource material is caused to restructure from a part of the template, thus forming the desired nanostructure at the predetermined point.
Said restructuring is in the form of a reassembling on the atomic scale of the nanosource material, resulting in qualitatively new properties relative to the properties of the nanosource material prior to the restructuring, said new properties being manifested in an altered, predefined response to external fields or forces.
The expression “qualitatively new properties” should here be taken to mean such fundamental changes in physical and/or chemical properties as, for example, a material which was transparent previous to the restructuring transitioning into being opaque, a conducting material becoming non conducting, a magnetic material becoming nonmagnetic, or materials changing optical and conduction responses by an effective restriction of the electron dynamics to lower dimensions, etc. Other examples of such transitions will be apparent to the man skilled in physics and/or chemistry. Said template preferably comprises two areas which have different properties with respect to their interaction with the nanosource material. In one embodiment of the present invention, this is done by one of the areas having stronger adhesive properties than the other with respect to the nanosource material.
By means of the method of the invention, virtually any nanostructure can thus be manufactured in-situ on a carrier, with the desired final shape of the nanostructure being obtained by giving the template the proper shape according to the desired shape of the nanostructure. The template may thus serve both as an aligning structure for the nanostructure, and as a bonding material for attaching the nanostructure to the carrier.
The invention thus also offers a nanostructure device, comprising a carrier and a nanostructure positioned on said carrier, said nanostructure extending along a predetermined path on the carrier, with the device additionally comprising an aligning structure, which aligns the nanostructure along said predetermined path on the carrier., the device also comprising a layer of material positioned on the carrier, said material being a bonding material for attaching the nanostructure to the carrier, which also serves as an aligning structure for the nanostructure.
In addition, the invention makes it possible to manufacture electronics devices, for example semiconducting devices, comprising nanotubes.
The invention will be described in closer detail below, with the aid of the appended drawings, in which:
a-1e schematically shows the main steps in a manufacturing process according to the invention,
a and 3b show other views of
a-b and 5a-b show the integration of a nanotube according to the invention in an electronics device, and
a-b, 8 and 9 show nanotube semiconductor devices which can be manufactured with the aid of the invention.
In
The main steps of the illustrative process will first be described briefly, following which a more detailed description of some of the steps will be given.
The main steps are as follows:
A material is chosen for a substrate 110, which will act as a carrier. There are two points, A and B on the substrate 110, which it is desired to connect via a nanostructure, in this case a nanotube, which extends along a predetermined path, in this case the shortest distance, i.e. a straight line, between said two points. however, it should become obvious to one skilled in the art that the invention enables a nanostructure to be designed which will follow more or less any predetermined path on the substrate or carrier.
On the substrate 110, a template 115 is formed, so that the template connects the two points A and B, i.e. the template or at least its edges coincides with the predetermined path. Since the nanostructure that it is desired to shape in this example of an embodiment is a nanotube, the template is given essentially rectangular dimensions, for reasons which will become apparent below. However, if it is desired to have a nanostructure of a different shape, this can easily be accomplished by means of the invention, by shaping the template in a manner according to the shape of the desired nanostructure.
The template 115 preferably comprises a first 120 and a second 130 area, said two areas being distinct from each other in that the material of the areas exhibit different properties in a way which will be described below.
On the template, a film 140 of nanosource material is formed. The materials of the two template areas 120, 130 exhibit different properties towards the nanosource material in their interaction with the nanosource material.
In this particular embodiment, the different interaction with the nanosource material lies in that the materials of the two template areas have different adhesive properties towards the nanosource material, the material of one area having stronger adhesive properties than the other. The significance of the different adhesive properties will become apparent in the next step, which in this example is the so called exfoliation of the film:
At least part of the film 140 is caused to exfoliate, in other words to “lift” at least in part from the template area 115. Due to the different adhesive properties of the different template areas 120, 130, if the exfoliation is done in a controlled manner according to the invention, only that part of the film 140 which is formed on the template area 130 which has the weaker adhesive properties towards the film will exfoliate, whereas that part of the film which is formed on the area 120 with the stronger adhesive properties will not exfoliate. Rather, this part of the film will serve as an “anchor” for the part of the film which exfoliates, i.e. a fixed point for the future nanostructure, in this case a nanotube 150, as shown in
It should be pointed out that the exfoliation of the film is a particular case of a more general aspect of the invention: parts of the film are caused to rise from the template, and to form into new structures. The action by the film when the template is shaped to make the film into a nanotube is exfoliation. However, a more general term for this step of the invention is that the film is made to “restructure” from the template, and to then form the desired final shape of the nanostructure.
An important feature of the present invention can be pointed out and emphasized here: the restructuring mentioned is in the form of a reassembling on the atomic scale of the nanosource material, resulting in qualitatively new properties relative to the properties of the nanosource material prior to the restructuring. These new properties are manifested in an altered, predefined response to external fields or forces.
The expression “qualitatively new properties” here refers to such fundamental changes in physical and/or chemical properties as, for example, a material which was transparent previous to the restructuring transitioning into being opaque, a conducting material becoming nonconducting, a magnetic material becoming nonmagnetic, etc. Other examples of such transitions will be apparent to the man skilled in physics and/or chemistry. The new properties of the material will be known in advance to those utilising the invention, so that the “post-transition” material will exhibit one or more desired physical or chemical properties.
With renewed reference to
Naturally, a number of conditions should be fulfilled in order for the process described above in connection with
In addition, the materials should fulfil the following requirements:
Another distinct possibility would be to use the substrate as a template area also, and to then introduce defects into the areas intended to have template properties, i.e. stronger or weaker bonding properties, the strength being determined by the material introduced as an impurity, and the amount of that material. Thus, one area of the substrate can act as the stronger bonding material, “the anchor”, and another area of the substrate can be induced with defects which make that area an area with weaker bonding properties, or vice versa.
However, the device shown in
a and 3b show other views of
b shows the device of
The points which are connected by the nanotube can, for example, be electrical contacts, if the nanotube is to be comprised in an electronics device.
The exfoliation of the film of nanosource material, i.e. the step between
Additionally, the exfoliation can be done by means of doping at least part of the material of the film of nanosource material, following its deposition on the template areas.
Furthermore, the additional energy does not need to be supplied in equal amounts over the area of nanosource material, the additional energy can, for example, be provided to a section of that part of the nanosource material which has been deposited on the area of the template which has the weaker adhesive properties.
The nanosource material can be deposited on the template area in a large number of different ways, which as such are known. Some such methods which can be mentioned as examples are sputtering or evaporation of the material.
One of many interesting materials to use as nanosource material is the element carbon, particularly if the nanostructures, in this example tubes, are to be used for conducting electrical current, i.e. if the nanotube is to be comprised in an electronics component or device. In such an application, it is particularly advantageous if the carbon is deposited on the template in the form of a graphene sheet. Graphene can be defined as single atomic layer graphite. Naturally, although the invention will be described using a film of one graphene sheet, one or more graphene sheets can be used in the film of the invention.
a and 4b show how a nanotube made according to the invention, using a graphene sheet as nanosource material, can be integrated into an electronics component or device. Since the nanotube is to be used for conducting current along a predetermined path between two points, contacts for external devices should be incorporated into the nanotube device, which will be explained in connection to
In
In
Turning now to graphene as a nanosource material, this material has at least one specific property which makes it extremely interesting for electronics applications: depending on the direction in which the film exfoliates, the graphene tube will exhibit different conducting properties. As shown in
The direction of exfoliation indicated by the arrow I1 in
A nanotube with “armchair” chirality will exhibit conducting properties similar to those of a metallic material, i.e. the nanotube will be highly conductive, whereas a nanotube with “zigzag” chirality will exhibit conducting properties similar to those of a semiconducting material.
In other words, using a nanotube consisting of a plurality of sections in its longitudinal direction, with the different sections having been formed by exfoliation of graphene sheets in different orientations, thus giving the different sections different chirality, it is possible to obtain components for a 5 semiconductor device, for example a transistor or a diode.
A step in the making of such a semiconductor device is shown in
As shown in
Thus, “sub-areas” 720 and 740 should, upon exfoliation, form a graphene nanotube with “armchair” chirality, and “sub-area” 730 should, upon exfoliation, form a graphene nanotube with “zigzag” chirality. In
When graphene film has been formed on the template areas, exfoliation is then carried out as described above. It can be shown that the different sections bond together as one continuous tube, with “bends” if and where the angles of the bonding areas differ from one another.
The different template areas 720, 730, 740, for the various sections of the nanotube can be formed on the substrate on the same side of the future nanotube, or, as shown in
It should be noted that the conducting properties of the different sections of the nanotube can be affected not only by giving the different sections different chirality: another way is to shape the template areas so that different sections of the nanotube will have different radii, thus leading to different cross-sectional areas, which will affect the conducting properties of the respective sections.
The invention is not limited to the embodiments which have been described above, but may be varied freely within the scope of the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
0104452 | Dec 2001 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/SE02/02461 | 12/30/2002 | WO | 00 | 12/14/2004 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO03/055793 | 7/10/2003 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
5665648 | Little | Sep 1997 | A |
6103399 | Smela et al. | Aug 2000 | A |
6350488 | Lee et al. | Feb 2002 | B1 |
6808746 | Dai et al. | Oct 2004 | B1 |
20040018139 | Mancevski | Jan 2004 | A1 |
20040043219 | Ito et al. | Mar 2004 | A1 |
Number | Date | Country | |
---|---|---|---|
20050100736 A1 | May 2005 | US |