CN1770469A - Field effect transistor using horizontally grown carbon nanotubes - Google Patents
Field effect transistor using horizontally grown carbon nanotubes Download PDFInfo
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- CN1770469A CN1770469A CN 200510107082 CN200510107082A CN1770469A CN 1770469 A CN1770469 A CN 1770469A CN 200510107082 CN200510107082 CN 200510107082 CN 200510107082 A CN200510107082 A CN 200510107082A CN 1770469 A CN1770469 A CN 1770469A
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Abstract
Disclosed is a method of horizontally growing carbon nanotubes, in which the carbon nanotubes can be selectively grown in a horizontal direction at specific locations of a substrate having catalyst formed thereat, so that the method can be usefully utilized in fabricating nano-devices. The method includes the steps of: (a) forming a predetermined catalyst pattern on a first substrate; (b) forming a vertical growth preventing layer on the first substrate, which prevents carbon nanotubes from growing in a vertical direction; (c) forming apertures through the vertical growth preventing layer and the first substrate to expose the catalyst pattern through the apertures; and (d) synthesizing carbon nanotubes at exposed surfaces of the catalyst pattern in order to grow the carbon nanotubes in the horizontal direction.
Description
Technical field
The present invention relates to the method for carbon nano-tube (carbon nanotube), be specifically related to a kind of method of horizontal growth carbon nano-tube, wherein can make this method can be used to make nano-device at the suprabasil specific location along continuous straight runs that is formed with catalyst carbon nano-tube optionally.
And, the present invention relates to a kind of method of horizontal growth carbon nano-tube, wherein form the catalyst of the shape of nano dot or nano wire, make at ad-hoc location carbon nano-tube optionally, thereby this method can be used to make nano-device effectively at the ad-hoc location of hope.
In addition, the present invention relates to a kind of field-effect transistor, wherein in the horizontal direction carbon nano-tube form to obtain the carbon nano-tube bridge of field-effect transistor (FET), and in the direction magnetization and source electrode that forms the carbon nano-tube bridge therebetween and the catalyst that drains and contact of hope, so that obtain Spin Valve (spin valve) and single-electronic transistor (SET) simultaneously.
Background technology
Carbon nano-tube has the structure of One-dimensional Quantum line and has favorable mechanical and chemical characteristic.And, known that carbon nano-tube shows absorbing electrical characteristics, for example the quantum transport phenomena.In addition, owing to had been found that other special nature recently, carbon nano-tube has received a lot of concerns as a kind of new material except that above-mentioned characteristic.
In order to utilize the good characteristic of this material, must first proposition can re-execute the carbon nano-tube manufacturing process of (re-executable).But, in existing technology, made carbon nano-tube after, be placed into them one by one the position of hope.Therefore, for carbon nanotubes grown being placed into the existing technology of desired location, being difficult to apply it to electronic component or height integrated component, and having carried out a lot of research and development now, so that overcome this problem with " individual processing pattern ".
In addition, in vertical-growth method as a kind of existing method of synthesizing carbon nanotubes, in the substrate 2 that is formed with catalyst figure 4 with the shape of the wheatland of neat layout at vertical direction carbon nano-tube 6.For the vertical-growth method, there have been a large amount of reports.
But, for carbon nano-tube is used as a kind of nano-device with new function, consider from application facet, with respect to the vertical-growth technology, a kind of can optionally the technology of carbon nano-tube be more useful and more people are required in the horizontal direction at ad-hoc location.
Shown first part of report that Hong Jie Die done (see Nature, vol.395, page 878) among Fig. 2, wherein represented and to have treated between the interconnective composition metal carbon nano-tube flatly.Fig. 2 is the figure of method that is used to schematically show the horizontal growth carbon nano-tube of Hong Jie Die report.But Fig. 2 has shown not only in the horizontal direction but also significantly in vertical direction a large amount of carbon nano-tube of having grown.This is because carbon nano-tube is epontic from catalyst metal, and is growth randomly on all exposed surfaces of catalyst.
And, owing to found giant magnetoresistance (GMR) effect comprising in 1988 in the multilayer film of magnetic metal and nonmagnetic metal, extensively carried out research in the world about the magnetic metallic film.And, because electronics is present in the magnetic metal with the spin polarization state, can produce the polarization spinning current by utilizing this characteristic.Therefore, by utilizing spin degrees of freedom, dropped into a large amount of effort and understood and develop spin electric device (spintronics) or magnetic electron device as an important inherent characteristic of electronics.
Recently, the phenomenon of finding in the magnetoresistance effect system of nanostructure such as tunnel magneto (TMR) and giant magnetoresistance (GMR) has been applied in magnetic resistance (MR) magnetic head element and has dropped into and treat in the hard disk drive (HDD) of business-like computer.
In the case, TMR means a kind of phenomenon, wherein tunnelling current changes according to the relative direction of magnetization of the ferromagnetic material in the knot with ferromagnet/dielectric (semiconductor)/ferromagnet structure, and have than bigger magnetic resistance ratio of other magnetic resistance and bigger field sensitivity, make people conduct a research energetically, in the material of MAGNETIC RANDOM ACCESS MEMORY of future generation (MRAM) or reluctance head, to utilize this phenomenon.But, the reproducibility of the formation of dielectric layer and knot impedance reduce to become serious problem.
Current, a lot of scientists of magnetic application are just utilizing in downfield the Spin Valve that shows the magnetic resistance phenomenon and magnetic tunneling junction (MTJ) in the research of carrying out the MRAM manufacture method energetically.
Summary of the invention
Therefore, the present invention is devoted to address the above problem, the method that the purpose of this invention is to provide a kind of horizontal growth carbon nano-tube wherein can make this method can be used to make nano-device at the suprabasil specific location along continuous straight runs that is formed with catalyst carbon nano-tube optionally.
Another object of the present invention provides a kind of method of horizontal growth carbon nano-tube, wherein form the catalyst of the shape of nano dot or nano wire at the ad-hoc location of hope, make that this method can be used to make nano-device effectively thus at ad-hoc location carbon nano-tube optionally.
Another object of the present invention provides a kind of field-effect transistor, wherein in the horizontal direction carbon nano-tube to form the carbon nano-tube bridge, thereby obtain field-effect transistor (FET), and in the direction magnetization and source electrode that forms the carbon nano-tube bridge therebetween and the catalyst that drains and contact of hope, so that obtain Spin Valve and single-electronic transistor (SET) simultaneously.
According to an aspect, the invention provides a kind of method of horizontal growth carbon nano-tube, this method may further comprise the steps: (a) form predetermined catalyst figure in first substrate; (b) form vertical-growth in first substrate and prevent layer, this prevents that layer from preventing that carbon nano-tube from growing in vertical direction; (c) prevent that by vertical-growth the layer and first substrate from forming a plurality of apertures to expose the catalyst figure by aperture; (d) at the exposed surface synthesizing carbon nanotubes of catalyst figure, so that carbon nano-tube in the horizontal direction.
In the case, the aperture that forms among the step c is the through hole type, and promptly aperture passes completely through vertical-growth and prevents the layer and first substrate, or the well type, promptly only partly corrodes first substrate, makes aperture pass vertical-growth and prevents layer and a part of first substrate.
According to another aspect, the invention provides a kind of method of horizontal growth carbon nano-tube, this method may further comprise the steps: (i) form mask in the first suprabasil precalculated position; (j) on the mask that forms in first substrate and first substrate, form the catalyst figure; (k) form vertical-growth in first substrate and prevent layer, this prevents that layer from preventing that carbon nano-tube from growing in vertical direction; (l) from vertical-growth prevent the layer and first substrate remove mask so that form aperture and expose the catalyst figure; (m) at the exposure position synthesizing carbon nanotubes of catalyst figure, so that carbon nano-tube in the horizontal direction.
According to another aspect, the invention provides a kind of method of horizontal growth carbon nano-tube, this method may further comprise the steps: form the catalyst figure in predetermined two-dimensional arrangement mode in first substrate; Manufacturing is used to prevent orthotropic second substrate of carbon nano-tube, the hole with predetermined arranged in form; Being used to prevent that orthotropic second substrate of carbon nano-tube is placed on first substrate with catalyst figure with predetermined gap; Synthesizing carbon nanotubes on the catalyst figure is so that carbon nano-tube flatly.
According to another aspect, the present invention also provides a kind of method of horizontal growth carbon nano-tube, and this method may further comprise the steps: form nano dot or the nemaline catalyst of nanometer in a substrate; Growth of composition prevents layer on nano dot or the nemaline catalyst of nanometer, grows in vertical direction so that prevent nano dot or nano wire; And on nano dot or nano wire carbon nano-tube optionally in the horizontal direction.
In the case, utilize method for stamping or self-assembling method patterning nano point or the nemaline catalyst of nanometer.
In addition, growth prevents that layer from can comprise silicon nitride (SiN) and silica (SiO by being selected from
2) group in the dielectric film that constitutes of a kind of compound form, perhaps can comprise palladium (Pd), a kind of metal formation in the group of niobium (Nb) and molybdenum (Mo) by being selected from.
According to another aspect, the present invention also provides a kind of method of horizontal growth carbon nano-tube, and this method may further comprise the steps: form the nemaline catalyst of nanometer in substrate; Utilization comprises that the semiconductor technology of photoetching process forms growth and prevents that layer, this growth from preventing layer and substrate interval predetermined gap on the nemaline catalyst of nanometer; Utilize wet corrosion, in not forming the zone that prevents layer of growing, remove the nemaline catalyst of a part of nanometer; And utilize chemical gas-phase deposition method, and substrate carbon nano-tube in the horizontal direction between the growth of the predetermined gap catalyst that prevents to form under the layer at interval.
In addition, according to another aspect, the present invention also provides a kind of field-effect transistor, comprise: source electrode, drain electrode, and the carbon nano-tube bridge between source electrode and the drain electrode, the carbon nano-tube bridge by between source electrode and the drain electrode in the horizontal direction carbon nanotubes grown forms, it is mobile to make field-effect transistor can control electronics.
In the case, the carbon nano-tube bridge that forms between source electrode and drain electrode comprises the carbon nano-tube with characteristic of semiconductor.
And, on the carbon nano-tube bridge that forms between source electrode and the drain electrode, form a plurality of gate carbon nanotubes, intersects with carbon nano-tube bridge between source electrode and the drain electrode, form the mobile of quantum dot (quantum point) and Control current so that produce energy barrier.
And when the gate carbon nanotube bridge formed grid, quantum dot had by using the size of public terminal control.
In addition, field-effect transistor also comprises first and second leads, first and second leads can by electric current and be separately positioned on source electrode and drain electrode on so that at the direction magnetization of hope and source electrode and the catalyst that drains and contact.Second lead that first lead that is provided with on the source electrode and drain electrode go up the to be provided with layout that is parallel to each other.
Description of drawings
After having read following detailed description in conjunction with the accompanying drawings, can clearer understanding be arranged to above-mentioned purpose of the present invention and further feature and advantage, in the accompanying drawings:
Fig. 1 is the figure that schematically shows the conventional method of vertical-growth carbon nano-tube;
Fig. 2 is the figure that schematically shows another conventional method of the horizontal growth carbon nano-tube that Hong Jie Die discloses;
Fig. 3 A is the figure that shows according to the method for one embodiment of the invention horizontal growth carbon nano-tube to 3D;
Fig. 4 is the perspective view of the object made by the method that Fig. 3 A shows in the 3D;
Fig. 5 A and Fig. 5 B are cutaway views, pass and well structure have been shown respectively, in pass structure, aperture passes the pass structure that vertical-growth prevents the layer and first substrate, in well structure, keep a part of first substrate and be not corroded, prevent the layer and first substrate so that each aperture not exclusively passes vertical-growth;
Fig. 6 A to 11 is the figure that are used to show according to the different shape of the carbon nano-tube of the method institute horizontal growth of horizontal growth carbon nano-tube of the present invention;
Figure 12 A and 12B are the figure that is used for display structure, wherein metal are carried out composition to form a knot or a plurality of knot with method horizontal growth carbon nano-tube by horizontal growth carbon nano-tube according to the present invention;
Figure 13 A is to schematically show the figure of another method of horizontal growth carbon nano-tube in accordance with another embodiment of the present invention to 13D;
Figure 14 A is to schematically show the figure of another method of horizontal growth carbon nano-tube in accordance with another embodiment of the present invention to 14C;
Figure 15 A is to schematically show by the method for horizontal growth carbon nano-tube according to the present invention figure in the process of desired location horizontal growth carbon nano-tube to 15C;
Figure 16 A is to be presented at the optionally figure of the method for carbon nano-tube of horizontal direction to 17D, wherein catalyst metal is formed the nano wire shape, and the position of formation catalyst can be controlled by wet corrosion;
Figure 18 A and 18B are the figure that is used to form the nano-imprint process of nano dot or nano wire in the method that is illustrated schematically in according to horizontal growth carbon nano-tube of the present invention;
Figure 19 is the figure that is used to form the self-assembling method of nano dot or nano wire in the method that is illustrated schematically in according to horizontal growth carbon nano-tube of the present invention;
Figure 20 schematically shows the figure of utilization according to the structure of the Spin Valve single-electronic transistor of carbon nano-tube of the present invention;
Figure 21 is the perspective view according to Spin Valve single-electronic transistor of the present invention shown in Figure 20;
Figure 22 schematically shows the figure of Spin Valve single-electronic transistor in accordance with another embodiment of the present invention;
Figure 23 to 26 is figure of the various field-effect transistors that form of the method by horizontal growth carbon nano-tube according to the present invention that schematically shows.
Concrete preferred embodiment
From below in conjunction with can be to above and other objects of the present invention the description of the drawings, characteristic and advantage have clearer understanding.
Fig. 3 A is to show the figure of the method for horizontal growth carbon nano-tube according to an embodiment of the invention to 3D, and Fig. 4 is the perspective view of the object made by the method that Fig. 3 A shows in the 3D.
Referring to Fig. 3 A to 4, may further comprise the steps: (a) in first substrate 10, form predetermined catalyst figure 12 according to the method for horizontal growth carbon nano-tube of the present invention; (b) form vertical-growth in first substrate 10 and prevent layer 14, this prevents that layer from preventing that carbon nano-tube from growing in vertical direction; (c) prevent that by vertical-growth layer 14 and first substrate 10 from forming aperture 16 to expose catalyst figure 12 by aperture 16; (d) synthesizing carbon nanotubes on the exposed surface 18 of catalyst figure 12 is so that carbon nano-tube in the horizontal direction.
According to the difference of purpose, first substrate 10 and vertical-growth prevent that layer from 14 can adopt various materials, silicon for example, and glass, silica is coated with the glass of tin indium oxide (ITO).
For above-mentioned catalyst, can use can carbon nano-tube various materials, comprise metal, alloy, superconducting metal and other particulate metal.And, can utilize photoetching, spraying plating, technologies such as evaporation form predetermined pattern 12 with these materials.
In the case, can utilize laser drill, methods such as wet corrosion and dry corrosion form the aperture 16 of the ad-hoc location that is positioned at the catalyst figure.Simultaneously, in more detail, aperture 16 can be a pass, promptly shown in Fig. 5 A, aperture 16 passes vertical-growth and prevents layer 14 and first substrate 10, or the well type, promptly shown in Fig. 5 B, do not corrode and keep the part of first substrate 10, make each aperture 16 not exclusively pass vertical-growth and prevent the hole 14 and first substrate 10.
Then, being placed into the equipment that is used for synthesizing carbon nanotubes, and synthesize, make only each carbon nano-tube of growth on the exposed surface 18 of the catalyst figure that is exposed to source atmosphere by Fig. 5 A of above-mentioned prepared or the object shown in Fig. 5 B.That is, only at the horizontal direction carbon nano-tube parallel with first substrate 10.
In the case, when synthesizing carbon nanotubes, can use following method, for example catalyst thermolysis process, plasma gas phase deposition process and heated filament gas-phase deposition method.In addition, can use hydrocarbon as raw material, for example methane, acetylene, carbon monoxide, benzene and ethene.
Simultaneously, Fig. 6 A, 6B and 11 shows the carbon nano-tube by the different shape of the method horizontal growth of horizontal growth carbon nano-tube according to the present invention.
Fig. 6 A and 6B are presented at carbon nanotubes grown 20 on the linear pattern catalyst figure 12, and wherein the predetermined portions at the catalyst figure forms aperture.In the case, by suitably controlling generated time, can obtain the carbon nano-tube 20 of bridge architecture alternatively, wherein the exposed surface that faces toward mutually of catalyst figure 18 interconnects by carbon nano-tube, the carbon nano-tube of the suspended structure that perhaps gains freedom alternatively, the exposed surface 18 that wherein faces toward does not mutually connect mutually.
Simultaneously, the area of the particulate on the catalyst surface that can expose by control or the diameter that size is determined institute's carbon nanotubes grown 20, and can make the catalyst surface of exposure have various surface state by the condition of change formation figure or by subsequent treatment (for example plasma treatment and acid treatment).Therefore, by above-mentioned technology, two carbon nano-tube 20 of on single exposed surface, can growing at least, and shown in Fig. 6 B, carbon nanotubes grown 20 can have different structures on the exposed surface that faces toward mutually 18 of catalyst figure, be different diameters, different spinning behaviour (chirality) or the like.
Fig. 7 A wherein forms aperture to the carbon nano-tube that 7D is presented at horizontal growth on the chiasma type catalyst figure respectively on the intersection region of catalyst figure.
Identical with linear pattern catalyst figure, in this chiasma type catalyst figure, also can obtain the carbon nano-tube 20 of bridge architecture as shown in Figure 7A or the carbon nano-tube 20 of the free suspended structure shown in Fig. 7 C.In addition, shown in Fig. 7 C, carbon nanotubes grown 20 can have the diameter that differs from one another on the exposed surface that faces toward mutually of catalyst figure, and is shown in two carbon nano-tube 20 of can growing at least on the exposed surface as Fig. 7 B.And by a plurality of carbon nano-tube of growth on each exposed surface of catalyst figure, institute's carbon nanotubes grown can have the net form shown in Fig. 7 D.
In addition, shown in Fig. 7 A, the height of the catalyst figure by control vertical direction and horizontal direction, can be mutually carbon nano-tube 20 across, this can be used as a grid element.In addition, intersect carbon nanotubes grown Mechanical Contact mutually mutually,, can use this junction characteristic by element so that form an electricity knot (electric junction) that can directly in knot is analyzed, use.
In the case, as a kind of method of being convenient to form knot, can utilize the thermal enlargement/contraction of material.Because the synthetic normally temperature between 500 ℃ to 900 ℃ of carbon nano-tube is carried out, can be convenient to intersect contact between the carbon nanotubes grown 20 by utilizing thermal contraction phenomenon (taking place in the cooling stage after synthetic).
Fig. 8,9,10 and 11 are presented at radial catalyst figure respectively, circular catalyst figure, the carbon nano-tube of horizontal growth and have the structure of at least two grooves at least two linear catalyst figures, arranging in the rectangle catalyst figure, wherein aperture is respectively in the intersection region of figure, the inside of circle and the inside of rectangle form.
Fig. 6 A to 11 shows that it does not limit the scope of the invention, and can revise the catalyst figure to be applied to nano-device in more effective mode according to the different shape of the carbon nano-tube of horizontal growth of the present invention.
Simultaneously, in the structure that Figure 12 A and 12B show, metal 30 compositions and carbon nano-tube 20 according to the method horizontal growth of horizontal growth carbon nano-tube of the present invention are formed a knot or a plurality of knot.Therefore, can easily obtain the knot between carbon nano-tube 20 and the metal 30, and can form this knot at ad-hoc location alternatively.
In addition, by utilizing said method, can form carbon nano-tube/carbon nano-tube knot, carbon nano-tube/metal knot, and carbon nano-tube/semiconductor junction alternatively in the position of hope.
Simultaneously, Figure 13 A is to schematically show the figure of another method of horizontal growth carbon nano-tube in accordance with another embodiment of the present invention to 13D.
To 13D, the method for horizontal growth carbon nano-tube may further comprise the steps in accordance with another embodiment of the present invention referring to Figure 13 A: (i) precalculated position in first substrate 10 forms mask 40; (j) on the mask 40 that forms in first substrate 10 and first substrate 10, form catalyst figure 12; (k) form vertical-growth in first substrate 10 and prevent layer 14, this prevents that layer from preventing that carbon nano-tube from growing in vertical direction; (1) prevents that from vertical-growth layer 14 and first substrate 10 from removing mask 40, so that form aperture 42 and expose catalyst figure 12; And (m) synthesizing carbon nanotubes on the exposure position of catalyst figure, so that carbon nano-tube in the horizontal direction.
In this embodiment, the material of first substrate 10 and catalyst figure 12 forms the method for catalyst figure, with identical among the method for synthesizing carbon nanotubes and first embodiment.In addition, utilize the method such as evaporation to form mask 40 in substrate, this mask 40 can be by corrosion, and methods such as heating are easily removed.In addition, the catalyst figure can be formed different shape, comprise linear, X-shape, radiation, circle, and rectangle.Present embodiment also can obtain the carbon nanotubes grown in the horizontal direction shown in Fig. 6 A to 11.
Figure 14 A is to schematically show the figure of another method of horizontal growth carbon nano-tube in accordance with another embodiment of the present invention to 14C.
To 14C, the method for horizontal growth carbon nano-tube may further comprise the steps in accordance with another embodiment of the present invention referring to Figure 14 A: form catalyst figure 12 in predetermined two-dimensional arrangement mode in first substrate 10; Manufacturing is used to prevent the orthotropic isolation substrate 50 of carbon nano-tube, has the hole 52 that predetermined way is arranged; Vertical-growth is prevented that substrate 50 is placed in first substrate 10 with catalyst figure 12 with predetermined gap 54; And at catalyst figure 12 place's synthesizing carbon nanotubes so that carbon nano-tube flatly.
In the case, the kind of first substrate 10 and catalyst figure 12 in the present embodiment, the method for formation catalyst figure is identical with first embodiment with the method for synthesizing carbon nanotubes.In addition, can pass through laser drill, methods such as wet corrosion and dry corrosion are formed for preventing the hole 52 of orthotropic second substrate 50 of carbon nano-tube.Vertical-growth is being prevented substrate 50 is placed in the step above first substrate 10, one can carbon nano-tube the interval be fit to for the predetermined gap 54 between two substrates 10 and 50.And can between the bight of first and second substrates 10 and 50, spacer 56 be set, so that keep gap therebetween.
Simultaneously, Figure 15 A is in the method that is presented at according to horizontal growth carbon nano-tube of the present invention to 15C, utilizes to have nano dot or the nemaline catalyst of nanometer, at the schematic diagram of the process of the position of hope horizontal growth carbon nano-tube.
At first, referring to Figure 15 A, be formed with on the silicon base of oxide-film deposit with the catalyst metal of nano dot or nano wire shape composition.In the case, usually use with above-mentioned catalyst figure 12 identical materials as catalyst metal.
In addition, shown in Figure 15 B, deposit such as palladium (Pd) on nano dot or nano wire, niobium (Nb), molybdenum material or silicon nitride (SiN) film or silica (SiO such as (Mo)
2) insulating barrier such as film forms growth and prevent layer.This layer is used to prevent that carbon nano-tube from vertically growing from catalyst, and further as electrode (under the situation of metal).In the case, utilize the general semiconductor technology of photoresist process (PR technology) and photoetching process and so on to prevent layer with the growth of desirable shape composition.
Therefore, shown in Figure 15 C, be formed with the growth prevent in the substrate of layer pattern, can utilize chemical gas-phase deposition method from catalyst along continuous straight runs carbon nano-tube.
Figure 16 A is the figure that is presented at the method for horizontal direction selective growth carbon nano-tube to 17D, wherein catalyst metal is formed the shape of nano wire, and can control the formation position of catalyst by wet corrosion.
At first, shown in Figure 16 A and 17A, deposit is patterned into the nemaline catalyst metal of nanometer on the silicon base of oxide-film being formed with.In the case, usually use with above-mentioned catalyst figure 12 identical materials as catalyst metal.
In addition, shown in Figure 16 B and 17B, deposit such as palladium (Pd), niobium (Nb), molybdenum material or silicon nitride (SiN) film or silica (SiO such as (Mo)
2) insulating barrier such as film, the growth that forms the shape of nano dot or nano wire on catalyst prevents layer, preventing has predetermined gap between layer and the catalyst.This layer is used to prevent that carbon nano-tube from vertically growing from catalyst, and further as electrode (under the situation of metal).
Can utilize the general semiconductor technology of photoresist process and photoetching process and so on to prevent layer with the growth of desirable shape composition.In the case, Figure 17 B has shown this situation, wherein in forming the process of figure mistake has taken place, and has promptly exposed catalyst in undesirable zone in growth prevents the composition process of layer.
And, shown in Figure 16 C and 17C, utilize wet corrosion to remove and in not forming the zone that growth prevents layer, have a nemaline catalyst of nanometer (i.e. catalyst in desired area not).In the case, under the situation of carrying out wet corrosion, owing to carry out isotropic etch, catalyst metal is further prevented a layer internal corrosion (seeing Figure 16 C) to growth, makes growth prevent that the function (promptly prevent carbon nano-tube from growing in vertical direction) of layer from becoming more important.
In addition, different with the situation that forms catalyst with the nano dot shape, forming under the situation of catalyst with the nano wire shape, even when having carried out excessive corrosion, the catalyst that is used for carbon nano-tube still is retained in substrate, prevents layer so that form more effective growth.In addition, shown in Figure 17 B and 17C, even when in photoetching process, having formed growth mistakenly and prevent the figure of layer, also can utilize wet corrosion to handle the mistake that produces in the photoetching process.
Therefore, utilize chemical gas-phase deposition method, can be between the catalyst that under growth prevents layer, forms with predetermined gap carbon nano-tube flatly.
Simultaneously, in the embodiment shown in the 17D, can use following known method at Figure 15 A as the method that in substrate, forms nano dot or the nemaline catalyst figure of nanometer.
A kind of method is the nano-imprint process of utilizing shown in Figure 18 A and 18B.Figure 18 A and 18B are the figure that is used to form the nano-imprint method process of nano dot or nano wire in the method that schematically shows according to horizontal growth carbon nano-tube of the present invention.
The nano-imprint method is a kind of imprint process, wherein the mould with nano graph is pressed onto on the macromolecule membrane, and to form the macromolecule figure of nano-scale, it can be applied to the large tracts of land wafer, shown in Figure 18 A and 18B.The nano-imprint method is the technology that is used for making simply the figure with tens nano-scales, compares with the formation technology of the large-area nano figure that utilizes existing meticulous optical treatment technology, greatly simplifies.
In addition, can utilize self-assembling method shown in Figure 19 to form the catalyst figure of nano dot or nano wire, Figure 19 is the figure that is used to form the self-assembling method of nano dot or nano wire in the method that schematically shows according to horizontal growth carbon nano-tube of the present invention.
In above-mentioned self-assembling method, the upper surface of substrate that is made of the metal of golden Au or silicon Si and so on is coated specific material, this material can be absorbed into the surface and go up as the surface activity headgroup, major part is the organic molecule that absorbs in the monolayer, and then apply material in a kind of alkyl, can realize and being connected of material thereon to be applied.Then, coating thereon has surface base (surface group) material of the characteristic of film, makes and can make the hyperfine film that has from single layer to the various layer of a plurality of layers.
That is, apply the certain material that can be absorbed by substrate, and apply the material that is used for and treats the thin-film material bridge joint of deposit, then the hope material of deposition film.After the certain material deposit from the teeth outwards that can carry out chemical absorbing, utilize scanning tunnel microscope/atomic force microscope (STM/AFM) to its composition, thereby can obtain to have the hyperfine film of wishing figure.
Simultaneously, Figure 20 schematically shows the figure of utilization according to the structure of the Spin Valve single-electronic transistor of carbon nano-tube of the present invention, and Figure 21 is the perspective view according to Spin Valve single-electronic transistor of the present invention shown in Figure 20.By utilizing method can obtain following Spin Valve single-electronic transistor in substrate horizontal direction carbon nanotubes grown by above-mentioned horizontal growth carbon nano-tube.
Referring to Figure 20 and 21, in Spin Valve single-electronic transistor according to the present invention, at source electrode 210 and the carbon nano-tube that drains between 220 in the horizontal direction forming carbon nano-tube bridge 260, carbon nano-tube bridge 260 make can Control current the unit electronics flow.In the case, the source electrode 210 and the carbon nano-tube bridge 260 that forms between 220 that drains are made up of the carbon nano-tube with characteristic of semiconductor.
In addition, the source electrode 210 and the carbon nano-tube bridge 260 that forms between 220 that drains form on a plurality of gate carbon nanotubes 270 and 280, and gate carbon nanotube 270 and 280 is formed energy barrier of generation and forms quantum dot, and Control current is mobile.
In addition, in source electrode 210 and drain electrode 220, provide the lead 251 and 252 that can flow through electric current, so that magnetize and source electrode 210 and drain electrode 220 catalyst that contact in the direction of hope.In addition, be arranged on the source electrode lead 251 on the source electrode 210 and be arranged on drain conductors 252 in the drain electrode 220 layout that is parallel to each other.
Simultaneously, Figure 22 schematically shows the figure of Spin Valve single-electronic transistor in accordance with another embodiment of the present invention.
Referring to Figure 22, when a plurality of gate carbon nanotube bridges 470 and 480 form grid 430 and 440, by using the size of public terminal 490 control quantum dots.Other element in the present embodiment is with identical with 21 described elements with reference to Figure 20.
After this, will describe the operation of utilization according to the Spin Valve single-electronic transistor with said structure of carbon nano-tube of the present invention.
Referring to Figure 20 and 21, in the source electrode 210 and the carbon nano-tube bridge 260 that forms between 220 that drains, positive voltage is applied to the carbon nano- tube bridge 270 and 280 that is defined as first and second grids 230 and 240 respectively with characteristic of semiconductor.Therefore, may be inadequate at the electric charge of a C1 and C2, cause forming energy barrier at a C1 and C2.In the case, at source electrode 210 with drain between 220 and to form under the situation of carbon nano-tube bridge 260, the part between some C1 and the C2 and the peripheral part that forms quantum dot are isolated.
In addition,, consider suitable coercive force, be defined as I by transmission because the electrode of source electrode 210 and drain electrode 220 contacts with carbon nano-tube bridge 260 by transition metal catalyst (transition metal catalyst)
M1And I
M2Electric current, can be at the magnetization of the direction of hope and the source electrode 210 and 220 catalyst that contact that drain.
Utilize said method, can control the electronic spin of injecting source electrode 210.In the case, when between source electrode 210 and the some C1 and some C2 and carbon nano-tube bridge 260 parts between 220 of draining when being ballistic conductor (ballistic conductor), can keep inject electronic spin.
Therefore, under the situation that electronics conducts interviews to the quantum dot that forms between some C1 and the C2 by tunnelling (tunneling), the direction of magnetization according to source electrode 210 and drain electrode 220 is easy to produce tunnelling, and is not easy to produce tunnelling when spin direction is different when spin direction is identical.
As mentioned above, by the electric current of control, can obtain single-electronic transistor with spin dependence by carbon nano-tube bridge 260 transmissions of raceway groove.
Simultaneously, Figure 23 to 26 is figure of the various field-effect transistors that form of the method by horizontal growth carbon nano-tube according to the present invention that schematically shows, will the various structures of field-effect transistor be described below.
Figure 23 shows a field-effect transistor, wherein all is provided with grid in the both sides of carbon nano-tube.In this example, can use niobium (Nb), the metal of molybdenum (Mo) and so on prevents the electrode or the electrode layer of film as growth.In addition, as the catalyst layer of catalyst be set at source electrode and drain electrode electrode layer below.In the case, can use with above-mentioned catalyst figure 12 identical materials as catalyst, and use nickel (Ni) usually, the material of iron (Fe) and cobalt (Co) and so on.
In the case, gate electrode is set at the both sides of source electrode and drain electrode.And, utilize thermal chemical vapor deposition method (TCVD) synthesizing carbon nanotubes between gate electrode.Therefore, need a geometry designs that comprises space between the gate electrode, make can be between gate electrode synthesizing carbon nanotubes.In the case, the space between the grid preferably is designed to have elongated structure, and promptly a kind of length and narrow structure are so that the growth of controlling carbon nanotube when producing enough grid electric fields.
Figure 24 shows a field-effect transistor, and wherein grid structure is positioned at the bottom.In this example,, a resilient coating is set under catalyst layer because the height of the aspect ratio grid of catalyst layer is big, with convenient Height Adjustment and with the adhesion of the insulating barrier of wafer.
In addition, because carbon nano-tube has favorable elasticity, can utilize electric field to make the carbon nano-tube bending.In the case, degree of crook changes according to the kind and the length of carbon nano-tube.Although maximum flexion can be tens nanometers, expect the crooked several nanometers of carbon nano-tube usually.Therefore, structure described in Figure 23 is designed by following mode, makes distance between the grid than big tens nanometers of width of the catalyst that is used for carbon nano-tube.Under the situation of described ground of Figure 24 grid, a thin dielectric layer can be deposited on the gate electrode as required.Simultaneously, Figure 25 shows a structure, wherein carbon nano-tube is used as grid.
Simultaneously, when synthesizing carbon nanotubes, carbon nano-tube may be perpendicular to the superficial growth of electrode, and is difficult to position from hope to relative catalyst layer carbon nano-tube when carbon nano-tube has characteristic of semiconductor.In order to address these problems, a path of guide (guide) as the guiding carbon nano tube growth can be set, i.e. passage that is used for carbon nano tube growth, carbon nano-tube can in this path or passage, grow (seeing Figure 26) between catalyst layer.
In the case, can utilize the dry corrosion of reactive ion etching (RIE) and so on, on silicon oxide film, make the guide that is used for carbon nano tube growth very finely.Then, at two outgrowth catalyst of guide, deposition of electrode thereon then.And, on the guide next door grid is set.In addition, grid can be positioned on dielectric surface as shown in the figure, and gate electrode can be placed on the corrosion area resemble the catalyst layer, makes gate electrode to apply electric field at the height identical with the height of catalyst layer or carbon nano-tube.
Can make the structure shown in Figure 23 and 24 by Twi-lithography technology.But the structure shown in Figure 25 and 26 needs third photo etching technology.In the case, the structure shown in Figure 25 not only can be fabricated to field-effect transistor (FET), and can be fabricated to tunnel transistor (tunneling transistor).And, be set at least two carbon nano-tube under the situation of grid, what manufacture according to gate bias can be Kondo element or the single-electronic transistor (SET) that utilizes Kondo resonance.In structure shown in Figure 26, prevent that when synthesizing carbon nanotubes it from growing in undesirable direction, thereby reduce this defective.
Though shown and described the preferred embodiments of the present invention, it should be appreciated by those skilled in the art that to the invention is not restricted to these specific embodiments, under the situation that does not depart from true scope of the present invention, can carry out various variations to its element, improve and replace.
Claims (7)
1. a field-effect transistor comprises source electrode, drain electrode, and the carbon nano-tube bridge between source electrode and the drain electrode, the carbon nano-tube bridge by between source electrode and the drain electrode in the horizontal direction carbon nanotubes grown forms, make field-effect transistor can control the mobile of electronics.
2. according to the field-effect transistor of claim 1, wherein the carbon nano-tube bridge that forms between source electrode and the drain electrode comprises the carbon nano-tube with characteristic of semiconductor.
3. according to the field-effect transistor of claim 1, wherein on the carbon nano-tube bridge that forms between source electrode and the drain electrode, form a plurality of gate carbon nanotubes, intersects, form the mobile of quantum dot and Control current so that produce energy barrier with carbon nano-tube bridge between source electrode and the drain electrode.
4. according to the field-effect transistor of claim 3, wherein when the gate carbon nanotube bridge formed grid, quantum dot had by using the size of public terminal control.
5. according to the field-effect transistor of claim 1, further comprise first and second leads, first and second leads can pass through electric current, and are separately positioned in source electrode and the drain electrode, so that at the direction magnetization of hope and source electrode and the catalyst that drains and contact.
6. according to the field-effect transistor of claim 5, second lead that the is provided with layout that is parallel to each other is gone up in first lead that wherein is provided with on the source electrode and drain electrode.
7. according to the field-effect transistor of claim 1, wherein in the substrate of field-effect transistor, form a guiding groove, with the growth in the horizontal direction between source electrode and drain electrode of permission carbon nano-tube, thereby between source electrode and drain electrode, form the carbon nano-tube bridge in the horizontal direction.
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| KR100445419B1 (en) * | 2002-02-25 | 2004-08-25 | 삼성에스디아이 주식회사 | Cold cathode emission source |
| KR101219769B1 (en) * | 2009-08-18 | 2013-01-18 | 세종대학교산학협력단 | Carbon nanostructured material pattern and manufacturing method of the same, and carbon nanostructured material thin film transistor and manufacturing method of the same |
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