WO2004027108A2

WO2004027108A2 - Process of controllable synthesis of carbon films with composite structures

Info

Publication number: WO2004027108A2
Application number: PCT/CA2003/001355
Authority: WO
Inventors: Zoya Kosakovskaya; Alexandre Iarochenko
Original assignee: Ht Innovative Technologies, Llc
Priority date: 2002-09-17
Filing date: 2003-09-17
Publication date: 2004-04-01
Also published as: AU2003264212A8; WO2004027108A3; AU2003264212A1

Abstract

The present invention provides a process of controllable growth of pure carbon structures including planar films, of single-walled fullerenes (SWF), multi-walled fullerenes (MWF), well oriented single-walled nanotubes (SWNT) and multi-walled nanotubes (MWNT) on various substrates. Structures can be built up on the surface which include any combination of fullerenes, nanotubes, bent or inclined nanotubes with single or multiple bends in the nanotubes.

Description

PROCESS OF CONTROLLABLE SYNTHESIS OF CARBON FILMS OF COMPOSITE CARBON STRUCTURES

CROSS REFERENCE TO RELATED APPLICATIONS This patent application relates to, and claims the benefit of, United

States provisional patent application Serial No. 60/411 ,083 filed on

September 17, 2002, entitled PROCESS OF CONTROLLABLE

SYNTHESIS OF CARBON FILMS OF COMPOSITE CARBON

STRUCTURES, which is incorporated herein in its entirety.

FIELD OF THE INVENTION

This invention relates to a process of controllable growth of pure carbon films out of single-walled fuUerenes (SWF), multi-walled fuUerenes (MWF), well oriented single-walled nanotubes (SWNT) and multi-walled

nanotubes (MWNT) on various substrates and to the apparatus used

therein.

BACKGROUND OF THE INVENTION

FuUerenes and carbon nanotubes, which constitute a new and

unique class of materials, form the basic building or structural block of novel nano-scale technology of the 21^st century.

Carbon nanotubes can function as either a conductor such as a

metal, as a semiconductor or a dielectric. Carbon nanotubes have shown

promise in many areas of application, including nano-scale electronic

devices, electron field emission, industrial chemistry and electrochemistry,

high strength materials, gas storage and many other aspects. Practically,

they surpass all known materials by their unique physical and chemical properties. However, the availability of these new carbon nano-scale

materials and the ability to produce films in different shapes and

configurations and also of high quality and in on a mass scale necessary

for practical commercialization, is still problematic.

Moreover, methods of synthesis of carbon films, which allow

controlling of parameters of fuUerenes and nanotubes during the process of growth, are needed. For example, methods are required to change the

angle of orientation of carbon nanotubes during their synthesis, to create

carbon films out of several homogeneous layers, each of which is characterized by certain parameters of fuUerenes and/or nanotubes, such as diameter, length, number of walls in fuUerenes and in nanotubes, angle

of orientation of nanotubes, etc.

Besides, it is important for practical technology to increase dimensions (area) of carbon films and ability to precipitate them on different substrates (metal, semiconductor, dielectric), and also absence of polluting additives, such as metallic catalytic particles, different forms of

carbon, for example amorphous carbon, etc.

At present, three main fabrication methods are used for synthesis of

fuUerenes and carbon nanotubes. They are as follows: arc discharge of

carbon rod, laser ablation of carbon and chemical vapor deposition (CVD)

of carbon-containing gas.

The arc discharge and the laser ablation methods do not allow

synthesis of carbon films and their precipitation on various substrates.

According to these methods, a mixture of multi-walled nanotubes,

amorphous carbon and graphite particles is formed. In order to form single-walled nanotubes, metal particles are added to the source. These

particles are injected into the steam phase of carbon and serve as a

catalyst. During formation of single-walled nanotubes, metallic catalytic

particles, for example Ni, Co, Fe etc., which pollute the initial product, are

injected into a vapor phase of carbon. It is still not possible to control size

and orientation of nanotubes, and also to control these parameters during

formation of nano-scale product. Existing methods of production are time

consuming and expensive. For example, they require high expenses,

including ones for accurate cleaning of nano-scale products at final stages. This is greatly reflected on the price of a product, which depends on purity

of a product.

In the CVD method, the necessary for the growth of films carbon

medium is formed as a result of chemical decomposition of carbon- containing bonds. Thus, products of decomposition will always pollute carbon films.

The CVD method does not allow controlling parameters of structure

during the process of film growth. For example, after growth of the fullerene homogeneous layer, this method does not allow to start growth of

the nanotubes layer, to change the angle of nanotubes orientation, etc.

The carbon arc method is the most common way to produce

fuUerenes and carbon nanotubes. This method creates nanotubes by the

arc-vaporization of two carbon rods placed end-to-end and separated by a

distance of approximately 1 mm. A direct current of 50 - 100 A, driven by

approximately 20 V, creates a high temperature discharge between the

two electrodes (W. Kratschmer, L.D. Lamb, K. Fostiropoulus, D.R. Huffman, Nature 347 (1990) 354; lijima and T. Ichihashi, Nature 363

(1993) 603). The discharge vaporizes one of the carbon rods and forms a

small rod-shaped deposit on the other rod. The yield by arc discharge

method is low.

In United States Patent No. 5,482,601 issued on January 9, 1996,

carbon nanotubes are produced by successively repositioning an axially

extending rod-like carbonaceous anode in relation to a cathode surface such that a tip end surface of the anode successively faces different

portions of the cathode surface. Carbonaceous deposits are scraped and collected. Excess amorphous carbon lumps are also produced along with

carbon nanotubes. Thus, they need complex purification processes.

In United States Patent No. 5,753,088 issued on May 19, 1998,

carbon nanotubes are produced by submerging carbonaceous anode and cathode electrodes in liquid nitrogen or other suitable liquefied materials such as helium or hydrogen (they must be ultra pure). Passing a direct current between electrodes to strike a plasma arc between anode and

cathode erodes carbon from the anode and deposits carbon nanotubes on

the surface of the cathode. Examination of materials scraped from the core of the cathode by electron microscopy has shown that carbon multi-walled

tubes and bundles of single-walled tubes possess nanometer (30 - 80 nm)

diameters and micrometer lengths.

The apparatus and method comprising novel electrodes for use in

arc discharge techniques were disclosed in United States Patent No.

6,063,243 issued May 16, 2000. The electrodes have interior conduits for

delivery and withdrawal of materials from the arc region, where product is formed. The anode (compound anode) is optionally made from more than one material. The materials assist by providing reaction ingredients and a catalyst or affecting the reaction kinetics. The disclosed method is used for producing nano-scale particles and tubes, comprising essentially materials chosen from the group 6-BN, BC₂N or BC₃.

A second method using laser ablation, a laser is used to vaporize the carbon that is being condensed in the form of carbon nanotubes. A laser ablation system disclosed in United States Patent No. 6.331.690 B1 issued December 18, 2001 produces SWNT from carbon vapor in the presence of Ni, Co, Pt, Pd or alloys containing at least two said materials.

The carbon vapor and the catalyst vapor are constantly generated from a carbon pellet and a catalyst pellet under radiation of YAG laser beams so that the SWNTs are constant in diameter.

One obvious connection between these two methods (arc discharge and laser ablation) is that both require a small percentage of transition metal (Co or Ni) to co-condense with the carbon (Chemical Physics Letters 260, 471 - 475). These catalytic particles pollute nano-scale product. Moreover, excess amorphous carbon lumps are also produced along with carbon nanotubes and they need expensive and complex purification processes. For example, the price of fuUerenes depends on the purity.

These two methods are not able to control the parameters of length and diameter of the nanotubes. It is impossible to manufacture a carbon film on different substrates consisting of SWF, MWF (onions), SWNT, MWNT and multilayer film comprising a layer of said nano-scale particles. A third method of chemical vapor deposition (CVD) is entirely

distinct from the catalytic formation of nanotubes by laser ablation and arc

discharge. In this method a carbon nanotube film is produced by using a

metal-catalyst (Ni, Co, Mo, etc.) in circumstances of chemical

decomposition of carbonaceous materials.

United States Patent No. 6,331 ,209 B1 describes a method of

formation of purified carbon nanotubes, in which graphitic phase or carbon

particles are removed by plasma etching. Carbon nanotubes layer is being

grown on a substrate using high-density plasma CVD. The substrate is an amorphous silicon or poly-silicon substrate, on which a catalytic metal layer is formed. A hydrocarbon series gas may be used as a plasma

source gas for the growth of the carbon nanotube layer.

The invention described in United States Patent No. 6,346,303 B1 provides a process for synthesizing parallel-aligned one-dimensional

nanosubstances. A membrane with channels serves as the host material for the synthesis. Channels of the membrane have a diameter of 30 - 35

nm. Parallel-aligned nanosubstances can be synthesized in these channels over a relatively large area (~ 1 cm²) by using an electron

cyclotron resonance chemical vapor deposition (ERC-CVD) of the precursor gas.

According to the ERC-CVD system, different nanosubstances can

be synthesized by using a suitable precursor gas. For example, possible

nanosubstances include carbon-based nanosubstances, silicon

nanosubstances, GaN nanosubstances, BCN nanosubstances and

tungsten nanosubstances. When the precursor gas includes carbon- containing gas (C_xH_y, where x and y are positive integers), carbon-based

nanosubstances can be synthesized.

United States Patent No. 6,333,016 B1 discloses a method of

manufacturing of carbon nanotubes by contacting, in a reactor cell,

metallic catalytic particles with an effective amount of a carbon-containing

gas at a temperature sufficient to catalytically produce carbon nanotubes,

wherein a substantial portion of carbon nanotubes are SWNT and other

portion (up to 50%) can be MWNT. Catalytic particles contain at least one

metal from group VIII and at least one metal from group Vlb. The amount of carbon or amorphous carbon and other solid residues (in terms of

weight) is less than 40% of weigh of the total solid carbon product formed

during the process.

As shown in transmission electron microscopic images, carbon nanotubes have a shape of a fiber (wire) with an external diameter of about 0.7 - 5 nm (SWNT) and about 2-50 nm (MWNT). This is clearly seen in large quantities of catalytic particles, carbon or amorphous carbon

in the shown images.

United States Patent No. 6,350,488 B1 discloses a method of synthesizing carbon nanotubes, which includes forming of metal catalyst

layer over a substrate. The metal catalyst layer is etched to form isolated

nano-sized catalytic metal particles; and carbon nanotubes, only vertically

aligned over the substrate, are grown from respective isolated nano-sized

catalytic metal particles by thermal CVD of a carbon source gas. The

etching gas may be ammonia, hydrogen or hydride. As disclosed, this

method of synthesis can produce carbon nanotubes with a diameter from a few nanometers to hundreds nanometers and with a length from a few

micrometers to hundreds of micrometers. At the same time, high

temperature of the substrate significantly limits choice of the substrate

material.

The objective of the United States Patent No. 6,361 ,861 B2 is to

provide methods for the synthesis of dense arrays of vertically well-aligned carbon nanotubes on prepared substrates, where each carbon nanotube is

simultaneously and completely filled with conductive filler. This method

includes steps of depositing a growth catalyst onto a conductive substrate to form the prepared substrate, creating a vacuum within a vessel, which

contains the prepared substrate, flowing H₂ / inert gas (e.g. Ar) within the vessel, increasing pressure within the vessel and increasing temperature

of the substrate and then changing the H₂ /Ar gas to ethylene gas so that ethylene gas flows within the vessel. As it is clearly seen from the images, the carbon nanotubes have a diameter of 300 - 350 nm.

A common disadvantage of methods discussed above is that the

vapor phase of carbon, from which carbon nanotubes are obtained, is

formed by a single source and the parameters of this vapor phase (temperature and concentration (density) of carbon particles) are

determined by parameters of this same source. As a result, temperature of

vapor phase (flow) and concentration of carbon particles are interlinked.

This does not allow directed change of vapor phase parameters and

obtaining of carbon films with required type of structure. In connection with the above, principally new method of controlled

synthesis of carbon films, suitable for commercial utilization, is described

in this invention.

SUMMARY OF THE INVENTION

An objective of this invention is to provide a method of controllable

formation of pure (free from impurities) carbon films over conducting, semiconducting or insulating substrates without using metallic catalytic

particles. Another objective is to provide for growing of carbon films over a small or large (up to hundreds of cm²) surface of substrates. Carbon films (CF) comprised of one or more homogenous layers (single-layer (SLCF) or

multi-layer (MLCF) carbon films) have been grown by the method disclosed herein, wherein each layer can include the same fuUerenes or carbon nanotubes in controllable different forms such as SWF, MWF,

SWNT or MWNT.

Also the controllable method allows synthesis of carbon films

comprising non-homogenous or/and homogenous layers consisting of all

mentioned forms of fuUerenes or/and nanotubes. Other aspect of the present invention is that the new method of the

synthesis under low temperatures of the substrate (from the near-to-room

temperature to temperatures of up to ~ 500K and slightly over) is able to

control diameter of fuUerenes and diameter and/or length of nanotubes

during their growth. This method is also able to change the angle of

orientation of nanotubes in the range of ±45° towards to the perpendicular to the surface of substrates on which they are being grown. The angle of

nanotube orientation with respect to the substrate surface can be

controlled during growth of the nanotube. Carbon nanotubes are well

oriented and grown strictly linear or bent with different orientations, for

example vertically aligned or inclined.

The present invention provides a method of synthesizing pre¬

selected carbon structures on a substrate, comprising forming a carbon

vapor phase interfacial region adjacent to a surface of the substrate by directing at least one carbon particle flux to the surface, and controlling a

process of growth of the pre-selected carbon structures by controlling temperature and density of the at least one carbon particle flux and controlling an orientation of the at least one carbon particle flux with

respect to the surface of the substrate.

The present invention also provides a product comprising a pre- selected carbon structure selected from the group consisting of one or

more layers of planar carbon films, fuUerenes, carbon nanotubes and combinations thereof synthesized by a method including forming a carbon

process of growth of the pre-selected carbon structures by controlling

temperature and density of the at least one carbon particle flux and

controlling an orientation of the at least one carbon particle flux with

respect to the surface of the substrate.

The present invention also provides a product comprising at least

one layer of single-walled or multi-walled fuUerenes on a surface of a substrate and at least one layer of single-walled or multi-walled nanotubes

on the at least one layer of single-walled or multi-walled fuUerenes, the

single-walled nanotubes having a first cylindrical axis oriented substantially

perpendicular and to the surface of the substrate.

The present invention also provides a product comprising at least

one layer of single-walled or multi-walled fuUerenes on a surface of a substrate and at least one layer of single-walled nanotubes on the at least

one layer of single-walled or multi-walled fuUerenes, the single-walled

nanotubes having a first longitudinal section with a first cylindrical axis oriented substantially perpendicular to the surface of the substrate and the

single-walled nanotubes having a second longitudinal section inclined at a pre-selected angle to the first longitudinal section.

The present invention also provides a product comprising at least one layer of single-walled or multi-walled fuUerenes on a surface of a substrate and at least one layer of single-walled nanotubes on the at least

one layer of single-walled or multi-walled fuUerenes inclined at a preselected angle with respect to the normal to the surface.

The present invention also provides a product comprising at least one layer of single-walled or multi-walled fuUerenes on a surface of a

substrate and at least one layer of single-walled nanotubes on the at least

one layer of single-walled or multi-walled fuUerenes having a cylindrical

axis substantially perpendicular to the surface and at least one layer of

multi-walled fuUerenes on the at least one layer of single-walled nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which:

Figure 1 shows a cross-sectional view illustrating a two-layer carbon film produced from carbon fuUerenes and carbon nanotubes produced in accordance with the method of the present invention;

Figure 2 is a schematic view of the process of fullerene synthesis by the mixing of two carbon particle flows with "cold" condensation centers in the interface area; Figure 3a and Figure 3b are schematic illustrations of configurations similar to Figure 2 for obtaining carbon films comprised of carbon nanotubes with controllable angle of inclination from the axis of nanotubes

towards the substrate in the range Θ° = ± 45 ;

Figure 4 is a schematic illustration of apparatus used for the synthesis using evaporation of carbon by electron beam, also this apparatus can be used for the synthesis using evaporation of carbon by laser ablation, arc discharge and plasma discharge;

Figure 5 is a schematic illustration of another apparatus used for the synthesis of carbon nanotubes based on the outline in Figures 3a and 3b;

Figure 6a shows a scanning tunneling microscope (STM) image of a SWNT film on quartz and Figure 6b shows a high precision transmission electron microscope (HTEM) image of bundles of these SWNTs with d=1.07 nm; Figure 7a shows a scanning tunneling microscope (STM) image

and Figure 7b shows the profile of a nanotube film on single crystal

graphite substrate, the nanotube has a diameter is 6.3 A and the diameter

of a bundle is 5 nm; Figure 8a is an STM image of carbon nanotube layer on quartz

produced according to Example 2 discussed below;

Figure 8b shows a high precision transmission electron microscope

(HTEM) image of the carbon nanotubes of Figure 8a after their extraction

from the surface of the substrate and further dispersion by ultrasound;

Figure 9a shows a STM image of a carbon nanotube film on a quartz substrate;

Figure 9b shows a HTEM image of the carbon nanotubes of Figure

9a after their extraction from the surface of the substrate and further dispersion by ultrasound; Figure 10 is an SEM image of carbon film of carbon nanotubes

inclined on a single crystal of graphite substrate;

Figure 11 is an SEM image of carbon film of carbon nanotubes

grown on a silicon substrate with the nanotubes having a p-n junction; and

Figure 12 is a timing chart showing the process for obtaining

various nanoscale carbon films using the apparatus of Figure 5.

DETAILED DESCRIPTION OF THE INVENTION

Definitions:

As used herein, the phrase "cold carbon flux" or "cold carbon

particles" describes particles that are formed due to partial re-evaporation (re-reflection) of "hot carbon particles" from the surface of the substrate

(Fig.4). Naturally, this process depends on the temperature and the

material of substrate, which in their turn are determined from the required

(pre-selected) density of the "cold carbon flux" or "cold carbon particles". In

this case substrate temperature can be from 300 K and above, but not

exceeding 770K. Another method of forming the "cold carbon flux" or "cold

carbon particles" is shown in Fig.5 as a reflecting mirror 3. Generally, the

"cold carbon flux" or "cold carbon particles" can also form from an

independent source, for example, 24 in Fig.2 or 2 in Fig 5. As used herein, the phrase "cold condensation centers" relates to

cold carbon particles in the vapor phase interfacial region, used for forming fuUerenes.

As used herein, the phrase "hot carbon flux" or "hot carbon

particles" means particles that are formed by evaporation of carbon particles into the vapor phase by electron beam or by other method, for example, laser or arc discharge evaporation.

As used herein, the word "fullerene(s)" is a commonly accepted name for a special form of existence of super-molecules of carbon, for

example, C60, C120, etc., which are widely known in the scientific

literature.

The present invention provides a method for producing carbon

films, which include layers preferably made up of fuUerenes, oriented

nanotube structures or their combination. Referring to Figure 1 a bi-layer

carbon structure is shown generally at 10, which may be grown using the

method disclosed herein, and includes a layer of fuUerenes 14 grown on the surface of a substrate 12 and a layer of nanotubes 16 grown on top of

the layer of fuUerenes. The method of growth allows one to change directly

the structure during growth, for example, SWF to SWNT or MWF to MWNT

as well as the orientation of the longitudinal axis of the nanotubes in the

range of ±45° from the normal to the surface of the substrate 12 during the

process of growth of layers as shown in Figure 1. The diameter of the nanotubes may vary and may be 0.63 nm and above.

Figure 2 shows a schematic view the fullerene synthesis by mixing

of two carbon particle fluxes from two separate carbon sources with "cold" condensation centers in interface area of the substrate. The substrate 12

onto which the carbon films are grown is placed on a temperature controlled plate 20. A first carbon source 22 is aligned with the substrate 12 and a second carbon source 24 is positioned at an angle with respect

to the substrate 12. Emanating from carbon source 22 is a first hot flux 26 of saturated vapor phase carbon particles and emanating from carbon source 24 is a second cold flux 28 of saturated vapor phase carbon with

both fluxes 26 and 28 being directed toward substrate 12.

The "hot and cold carbon particles" may contain carbon atoms (C1 ), dimers of carbon (C2) ..., C6 and also compounds of a higher degree,

and in some cases microclumps and microparticles of carbon are also

possible.

The density and temperature of the carbon fluxes can be controlled

during the process of the film growth by changing modes of carbon

evaporation of the second carbon source 24. For example, such changes

may be achieved by changing temperature of the mirrors used to reflect the secondary particle fluxes, which changes the concentration of the cold

flux density, changing the type of substrate material, the angle of the

sources with respect to the substrate surface, etc. Further details are given

in the Examples. A general explanation is given in Figure 12 and also

Examples 1 - 5 give non-limiting examples.

The flow of "cold" carbon particle flux 28 is directed in such a way

that in the area near to the substrate surface (interface area) mixing of

both carbon flows occurs. As a result, an over-saturated vapor carbon

phase with condensation centers in the form of "cold" carbon particles is formed near the substrate's surface thus producing a super saturated carbon vapor interface 30 in the vicinity of the top surface of substrate 12.

A flux of "hot" carbon particles is formed by evaporation of graphite by for example electron beam bombardment.

In the configuration shown at 40 in Figure 3a the substrate 12 is at

an angle (theta) with respect to the first carbon source 22 while the second hot carbon source 24 produces a flow of "cold" carbon particles with controllable density and temperature by changing mode in the time of

carbon evaporation of the second source 24. Figures 2 and 3a display the

source 24 of "cold" carbon particles separately and "independently" from the source 22 of "hot" carbon particles. In Fig. 3b, flux of "cold" particles,

which is directed to the substrate 12, is formed due to partial re-reflection

(re-evaporation) of "hot" carbon particles from the mirror 48. The mirror 48

can be manufactured in a form of a substrate out of any material

(conductor, semiconductor or dielectric). For example, the "mirror" 48 can

be manufactured out of graphite, quartz, steel, titanium, copper etc. The mirror's temperature can be 300 K and above, depending on the required

value of relative ratio R of the "cold" flux particle density to "hot" flux

particle density. For example, if the temperature of "mirror" 48 is

approximately 300 K, then the relative density R ~ 1/59, i.e. there are

approximately 59 - 60 "hot" atoms of carbon for 1 "cold" atom of carbon. If

one were to raise the temperature of the mirror, then R increases, i.e. R >

1/59, and if to lower the temperature of the mirror, then R < 1/59.

The difference between Figure 3a and Figure 2 is following. In

Figure 2, the flux of "hot" carbon particles 26 is directed perpendicular to the substrate 12. As a result, during of the process of growth, carbon

nanotubes, oriented perpendicular to the surface of the substrate 12, are obtained. In Figure 3, the flux of "hot" carbon particles is oriented under

the angle Θ to the normal to the surface of the substrate. In this process,

nanotubes, oriented under the angle Θ to the normal to the substrate, are

obtained. In the process shown in Figure 3a, chirality and diameter of

nanotubes change, which differs from the process shown in Figure 2. By changing the angle Θ it is possible to vary orientation and properties of

nanotubes. If the angle Θ changes during the process of growth, boundary

(for example, p-n-p) can be obtained. It is shown graphically in Figure 1.

In the configuration shown at 44 in Figure 3b both flows of the carbon particle fluxes impinging on the substrate 12 are produced by a

single carbon source 46, which is a hot carbon source. Herewith, a flow of

"cold" carbon particles with controllable density and temperature is formed

by re-radiation of thermalized carbon particles from mirror-substrate 48. Changing mode re-radiation of the "thermal" carbon particles from mirror-

substrate in the time performs by the temperature and density control.

Since formation of fuUerenes takes place in the volume of over-

saturated carbon vapor phase, then the substrate material may be of any

type including conductor, semi-conductor or insulator. Therefore, the

present invention is advantageous in that it allows following: obtaining of

fullerene films with high content of fuUerenes; obtaining films out of multi-

walled fuUerenes; obtaining of films out of well-oriented single-walled

nanotubes (after forming of monolayer of fuUerenes, the flow of "cold" carbon particles is being turned off); obtaining films out of combination of

oriented single-walled and multi-walled nanotubes; obtaining films out of multi-walled nanotubes; obtaining of films out of nanotubes with varied

chirality in different areas of the length, including obtaining of p-n boundary in the single or multi-walled nanotubes with two sections; obtaining carbon structures out of layers of fuUerenes and nanotubes.

In one embodiment of the invention the various carbon

nanostructures may be grown using electron beam evaporation in vacuum

of pure carbon under conditions of autocatalysis in over-saturated vapor phase of carbon without using metallic catalytic particles and free from impurities. The method of electron beam evaporation of various materials

by the electron beam method is well known to those skilled in the art.

Simplified, this process is schematically shown in Figure 4. As a result of

this process, a directed flux of carbon vapor phase 60 is being formed. In

this context, the flux of hot carbon particles is called a flux of "thermal"

carbon particles. (See 60 in Figure 4.) A flux of "cold" carbon particles 64 is formed due to partial re-evaporation (re-reflection) of carbon from the

surface of substrate 12. Naturally, re-evaporation coefficient depends on

temperature and material of a substrate.

The substrate temperature may be controlled during film growth and

may be maintained at about 300 K and above depending on the material

of the substrate and on the required (set) density of a flux of re-evaporated

"cold" carbon particles. These "cold" particles are those centers of

condensation of a vapor phase of "hot" carbon particles in the interface area.

When the ratio of flow densities of "cold" and "hot" particle fluxes are selected to be close to R = 1 :60, the vapor phase is being condensed

in the form of fuUerenes, which deposit on the substrate 12 thereby producing the film of fuUerenes 32. Flux density is defined as a number (N) of carbon particles that passes through a unit of surface area (cm²) within

a unit of time (sec) - N/sec cm². In these materials a relative density of carbon particles was used. Here, flux density of "hot" carbon particles is

assumed to be equal to unity (1 ), and the relative density of "cold" carbon particles is assumed to be equal to R in relation to the "hot" ones. With R >

1 :60, surplus of condensation center occurs.

Carbon phases consist of fuUerenes and amorphous carbon. The

number of amorphous carbon phases increases with increase of R. With R

< 1 :60, deficit of condensation centers occurs. Carbonization of fuUerenes

takes place. The film consists of combination of fuUerenes, multi-walled

fuUerenes (onions) and appearance of amorphous carbon is possible. With

significant decrease of R, it is possible to obtain the film, which mostly consists of multi-walled fuUerenes with large number of walls. If during the

process of growth of carbon fuUerenes film, the flow of "cold" carbon

particles has been stopped, the directed flow of "hot" carbon particles

continues to grow appearing on the surface fuUerenes in the form of

nanotubes, oriented towards the flow. Having changed the angle between the substrate and the direction of the flow of "hot" carbon particles during

the process of growth of the nanotube film, it is possible to change the

longitudinal axis of orientation of the nanotube in the range of ±45° (Fig.3a

and 3b). The control of direction of the "thermal" carbon particles (angle

θ°) is achieved by changing angular position in a space of the substrate in

a range ± 45°.

The proposed scheme of synthesis of carbon films can be implemented in the apparatus schematically illustrated in Figure 4, where the flow of "thermal" carbon particles is formed by evaporation of carbon by an electron beam. Figure 4 is a schematic illustration of part of an

apparatus 50 for the synthesis of the hybrid carbon films using electron beam evaporation. A source of electrons 52 produces a beam of electrons

54, which is directed through a magnetic focusing lens 56 to focus the

electron beam onto the surface of a carbon target 58. Bombardment of the graphite target 58 by the electron beam produces a thermal carbon flux

60, which is directed toward substrate 12. A saturated carbon interface

region 62 is formed in front of the substrate 12 out of which a flow of re-

vaporized "cold" carbon particle flux 64 emanates directed toward

substrate 12. This flux of "cold" carbon particles 64 is formed in the

interface region 62 due to partial re-evaporation of carbon from the surface of substrate 12. Since the coefficient of re-evaporation depends on the

temperature and material of the substrate 12, it can be controlled by

changing the temperature of the substrate 12 or by changing the material

of the substrate. Figure 5 shows a more detailed schematic illustration of an

apparatus 70 for the controllable synthesis of carbon mono-scale films and

materials and includes a vacuum chamber 72 containing a first carbon

source 74 from which "hot" carbon particles are produced thereby

producing a carbon particle flux 76. The apparatus 70 includes a second source of carbon 78, which is inclined at an angle with respect to source

74, and there maybe several of these sources of "hot" carbon particles. A source of "cold" carbon particles is in the form of a mirror 80 which reflect carbon particles from source 74 that reach mirror 80 through a screen 82

which has an aperture 84 positioned in the screen so that a flux of carbon particles 86 passes through the aperture 84 and reflect off mirror 80. The reflected beam of particles forms a diverging flux 88 toward a mixing zone

90 located adjacent to the surface of the substrate 90 onto which the film is being grown. Apparatus 70 includes dual sets of vacuum pumps 94 and

96 with pump 94 being a preliminary pump for obtaining a pressure of P ~

10^"3 mm Hg and pump 96 being for obtaining a pressure of about P < 10^"6

mm Hg. There may be several screens such as screen 82 with apertures

all directing carbon particle fluxes to different mirrors. Substrate 90 may be

made of any material, (conductor, semiconductor or insulator) and the

temperature of substrate 90 is controlled using a heater/cooler 98 having a

tube 100 for passing heated or cooled fluid under the substrate. Alternatively heater/cooler 98 may be an electrically controlled

heater/cooler. Valves 102, 104 and 106 are used to control the pumping of

the vacuum chamber 72.

The present invention will now be illustrated using the following

non-limiting examples.

EXAMPLE 1

Using sources of vapor phase fluxes #1 and #3, single-layered film

with the thickness of 0.2 microns, made of single walled nanotubes normally oriented to the surface of a substrate, was precipitated on a

quartz (Figure 6) and graphite (Figure 7) substrate with dimensions of 20 x 20 mm² in an apparatus shown in Figure 5.

Pressure in the working chamber did not exceed 10^"6 torr. Directed flux of hot vapor phase of carbon was formed by the method of electron- ray vapor of carbon. Density of the flux did not exceed 10¹⁹/cm². Cold vapor phase was formed as a result of its reflection from a thermal mirror

(source 3). In this case, tungsten substrate with the temperature of 300 K

(Figure 5) was used as a thermal mirror 3. As a result of intermixing of hot and cold fluxes of carbon, a hot vapor phase with cold condensation centers with a ratio R ~ 1/59 was formed in the near-surface area. As a

result of condensation of the vapor phase, a layer of fuUerenes with

diameter of 0.63 nm was formed on the surface of graphite substrate and

a layer of fuUerenes with diameter of 1.07 nm was formed on the surface

of quartz. After fullerene layer has been formed, the cold vapor phase

source #3 (Figure 5) is being switched off by shutting the diaphragm 8 (flux

12 of cold particles stops). After the cold vapor phase source has been switched off, a directed flux of hot vapor phase was providing for the

growth of single-walled nanotubes, diameter and chirality of which were

defined by the precipitated layer of fuUerenes.

A scanning tunneling microscope (STM) image of the structure of

the nanotube film on quartz and also High Precision Transmission

Electronic Microscopy (HTEM) of the structure of nanotube bunches after their extraction from the surface of substrate and further dispersion by

ultrasound are shown in Figures 6a and 6b. Scanning Tunnel Microscopy

(STM) image of nanotube film on graphite and its profile are displayed in Figures 7a and 7b.

EXAMPLE 2

A film consisting of combination of MWNT and SWNT oriented normal to the substrate surface was synthesized on the silicon substrate with the diameter of 100 mm.

Forming of such a film was taking place by the method described in

example 1 , but under the condition of a lower density of cold vapor phase

flux (1/59 > R > 1/160). Lack of condensation centers is the reason for graphitization of a part of fuUerenes (formation of MWNF) and as a result,

for formation of fullerene monolayer out of mixture of MWNF and SWNF,

which after switching off the source of a cold vapor phase grow through as a mixture of MWNT and SWNT.

Figures 8a and 8b display STM image of the structure of nanotube

layer on quartz, and also High Precision Transmission Electronic Microscopy (HTEM) of the nanotube structure after their extraction from

the surface of substrate and further dispersion by ultrasound.

EXAMPLE 3

Using sources of vapor phase fluxes #1 and #3, a film with the

thickness of 0.5 μm, made of multi-walled nanotubes, normally oriented to

the surface of a substrate, was precipitated on a quartz substrate with dimensions of 20 x 20 mm² in a device shown in Figure 5.

Formation of such a film was taking place by the method described

in Examples 1 and 2, but under the condition of even more low density of the cold vapor phase (1/160 > R). (Excessive) hot particles of the carbon vapor phase, which don't participate in forming of fuUerenes, are being

condensed on colder fuUerenes and, after their precipitation on the substrate (switching off the source of cold vapor phase), grow through in the form MWNT film.

Figures 9a and 9b display STM image of the structure of nanotube film on quartz, and also High Precision Transmission Electronic

Microscopy (HTEM) of MWNT structure after their extraction from the surface of substrate and further dispersion by ultrasound.

EXAMPLE 4

Using sources of vapor phase fluxes #1 and #3 (inclined), a film

with the thickness of 0.38 μm, made of single walled nanotubes with the

diameter of 10.7 A and oriented to the normal to the surface of a substrate

under the angle of ~ 30°, was precipitated on a silicon substrate in a

device shown in Figure 5 under conditions of the Example 1. An electron- microscopic image of cross-section of structure of the obtained film is shown in Figure 10.

EXAMPLE S Using sources of vapor phase fluxes #1 (continuous), #2 and #3

(inclined source of hot vapor phase of carbon), a film with the thickness of

0.38 μm, made of single walled nanotubes with the diameter variable by

the length, was precipitated on a silicon substrate with dimensions of 10 x 10 cm in a device shown in Figure 5 under conditions of the Example 1. As a result, a nanotube film with a p-n boundary will be obtained. An electron microscope image of a cross-section of structure of the obtained film is shown in Figure 11.

Although it is not shown in Figure 12, one or more layers of multi- walled fuUerenes can first be grown on the substrate or layers of multi- walled fuUerenes can be combined with layers of single-walled fuUerenes in any order depending on the mode of operation of the cold flux (density ratio R~1/60 produces single-walled fuUerenes and 1/160 < R 1/60 prduces multi-walled fuUerenes). The type of the top row of fuUerenes will define the type of nanotubes that can grow on top of it, i.e. single-walled nanotubes can only grow off the single-walled fuUerenes and multi-walled nanotubes can only grow off the multi-walled fuUerenes. Some of the possible combinations are shown in the diagram in Figure 12.

Figure 12 displays a general time diagram of obtaining of various nanoscale carbon films using for example the apparatus shown in Figure 5. It is noted that in order to grow the carbon nanotubes, at least one layer of fuUerenes, single-walled (shown as "on" in column I with R about 1/59)

or multi-walled (1/160 < R < 1/60), is first grown on the substrate surface

using the conditions in column I and then the processing conditions are

changed to those shown in column II to grow single-walled nanotubes on

the single-walled fuUerenes or multi-walled nanotubes on the multi-walled

fuUerenes which are substantially perpendicular to the surface of the substrate using a flux of hot carbon particles which is oriented normal to

the surface. Column III shows that in order to grow nanotubes which have

an inclined section the flux of cold carbon particles is stopped and the orientation of the flux of hot carbon particles is changed to impinge the

surface at an angle thereby giving the inclined nanotube sections. It will be understood that the combinations of carbon structures shown in Figure 12

are meant to be exemplary and are not meant to be limiting. Those skilled in the art will appreciate that there are numerous other combinations which are intended to fall within the scope of the invention. Any combination of

fullerenes/nanotube/multi-inclined nanotubes may be grown.

Single or multi-walled nanotubes, having a second inclined section are shown in Figure 12 with the first section being perpendicular to the

surface. However, these nanotubes can also be grown with the first

section inclined or tilted to the surface and the nanotubes may have

multiple sections each inclined at a different angle.

As used herein, the terms "comprises", "comprising", "includes" and

"including" are to be construed as being inclusive and open ended, and not

exclusive. Specifically, when used in this specification including claims, the

terms "comprises", "comprising", "includes" and "including" and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.

The foregoing description of the preferred embodiments of the invention has been presented to illustrate the principles of the invention and not to limit the invention to the particular embodiment illustrated. It is intended that the scope of the invention be defined by all of the embodiments encompassed within the following claims and their equivalents.

Claims

THEREFORE WHAT IS CLAIMED IS:

1. A method of synthesizing pre-selected carbon structures on a substrate, comprising: forming a carbon vapor phase interfacial region adjacent to a surface of the substrate by directing at least one carbon particle flux to the surface, and controlling a process of growth of the pre-selected carbon structures by controlling temperature and density of the at least one carbon particle flux and controlling an orientation of the at least one carbon particle flux with respect to the surface of the substrate.

2. The method according to claim 1 including controlling the process of growth of the pre-selected carbon structures by suitable selection of the substrate material and controlling substrate temperature.

3. The method according to claim 1 or 2 wherein controlling the

temperature and density of the at least one carbon particle fluxes includes producing and directing at least one flux of hot carbon particles to the

surface of the substrate, the at least one flux of hot carbon particles having

a first pre-selected density and first temperature, and producing and

directing at least one flux of cold carbon particles to the surface of the

substrate, the at least one flux of cold carbon particles having a second

pre-selected density, and a second temperature less than the first temperature.

4. The method according to claim 1 , 2 or 3 wherein the desired carbon structure is selected from the group consisting of one or more layers of planar carbon films, fuUerenes, carbon nanotubes and combinations thereof.

5. The method according to claim 4 wherein the fuUerenes are single- walled fuUerenes (SWF) or multi-walled fuUerenes (MWF), and wherein the carbon nanotubes are single-walled nanotubes (SWNT) or multi-walled nanotubes (MWNT) oriented perpendicular to the surface or inclined at least once, and wherein the single and multi-walled fuUerenes and single and multi-walled nanotubes may be grown in any combination on the surface.

6. The method according to claim 1 , 2, 3, 4 or 5 wherein the substrate is selected from the group consisting of insulators, semiconductors, semimetals and conductors.

7. The method according to claim 1 , 2, 3, 4, 5 or 6 wherein the density and temperature of the at least one flux of hot carbon particles is altered

by altering a mode of carbon evaporation from a carbon source.

8. The method according to claim 3 wherein the at least one flux of hot

carbon particles having a higher temperature than the at least one flux of

cold carbon particles is produced using electron beam evaporation from a carbon source.

9. The method according to claim 3 wherein the at least one flux of hot

carbon particles is two fluxes of hot carbon particles, the first flux of hot

carbon particles being produced from a first carbon source oriented with

respect to the substrate surface so that the first flux of hot carbon particles

is substantially perpendicular to the surface, and the second flux of hot

carbon particles being produced from a second carbon source being

inclined at a pre-selected angle to the substrate surface from the perpendicular, and wherein directing the first flux of hot carbon particles

toward the surface but not the second flux of hot carbon particles grows carbon nanotubes substantially perpendicular to the surface, and wherein

directing the second flux of hot carbon particles toward the surface but not the first flux of hot carbon particles grows carbon nanotubes inclined at the pre-selected angle with respect to the surface.

10. The method according to claim 3 wherein the desired carbon

structure is single-walled fuUerenes grown on the substrate, and wherein the at least one flux of hot carbon particles is one flux of hot carbon

particles oriented normal to the surface of the substrate, and wherein the at least one flux of cold carbon particles is one flux of cold carbon

particles, and wherein a ratio R of the second pre-selected density to the

first pre-selected density is about 1/60.

11. The method according to claim 3 wherein the desired carbon

structure is multi-walled fuUerenes, and wherein the at least one flux of hot carbon particles is one flux of hot carbon particles oriented normal to the

surface of the substrate, and wherein the at least one flux of cold carbon

particles is one flux of cold carbon particles, and wherein a ratio R of the

second pre-selected density to the first pre-selected density is in a range

from 1/160 < R < 1/60 whereby multi-walled flullerenes are grown on the

substrate.

12. The method according to claim 10 wherein after growing at least

one layer of single-walled fuUerenes, the one flux of cold carbon particles

is turned off and the one flux of hot carbon particles is directed at the substrate for a pre-selected period of time whereby single-walled nanotubes of pre-selected length are grown on the single-walled fuUerenes

having a first cylindrical axis oriented substantially perpendicular to the surface of the substrate.

13. The method according to claim 12 wherein after growing the first section of single-walled nanotubes substantially perpendicular to the

surface of the substrate the one flux of hot carbon particles is tilted at a pre-selected angle from the normal axis to the surface of the substrate for

a pre-selected period of time to grow a second section of the single-walled

nanotubes wherein the second section has a second cylindrical axis

inclined at the pre-selected angle to the first cylindrical axis.

14. The method according to claim 10 or 11 wherein after growing at

least one layer of single-walled fuUerenes, the one flux of cold carbon particles is turned off and the one flux of hot carbon particles is oriented at

a pre-selected angle off the normal to the surface of the substrate for a

pre-selected period of time to grow single-walled nanotubes having a

cylindrical axis inclined at the pre-selected angle to the normal to the

surface of the substrate.

15. The method according to claim 12 wherein after growing the single- walled nanotubes of pre-selected length having a first cylindrical axis

oriented substantially perpendicular and to the surface of the substrate the

one flux of cold carbon particles is again directed at the surface of the substrate, and wherein a ratio R of the second pre-selected density to the

first pre-selected density is in a range from 1/160 < R < 1/60 whereby multi-walled flullerenes are grown on the single-walled carbon nanotubes.

16. The method according to claim 13 wherein after growing the single-

walled nanotubes with the second section of the single-walled nanotubes having a cylindrical axis inclined at the pre-selected angle to the cylindrical

axis of the first section the one flux of cold carbon particles is again directed at the surface of the substrate, and wherein a ratio R of the

second pre-selected density to the first pre-selected density is in a range

from 1/160 < R < 1/60 whereby multi-walled flullerenes are grown on the

single-walled carbon nanotubes.

17. The method according to claim 15 wherein after the multi-walled

flullerenes are grown on the single-walled carbon nanotubes, the one flux of cold carbon particles is turned off and the one flux of hot carbon

particles is oriented normal to the surface of the substrate for a pre¬

selected period of time to grow multi-walled nanotubes of pre-selected

length having a first cylindrical axis which is substantially perpendicular to

the surface of the substrate.

18. The method according to claim 16 wherein after the multi-walled flullerenes are grown on the single-walled carbon nanotubes having the

second inclined section, the one flux of cold carbon particles is turned off

and the one flux of hot carbon particles is oriented normal to the surface of the substrate for a pre-selected period of time to grow multi-walled

nanotubes of pre-selected length having a first cylindrical axis which is substantially perpendicular and to the surface of the substrate.

19. The method according to claim 18 wherein after growing the multi-

walled nanotubes substantially perpendicular to the surface of the substrate for the pre-selected length to grow a first section the one flux of

hot carbon particles is oriented at a pre-selected angle off the normal to

the surface of the substrate for a pre-selected period of time to grow a second section the multi-walled nanotubes wherein the second section of

the multi-walled nanotubes have a cylindrical axis inclined at the pre¬

selected angle to a cylindrical axis of the first section.

20. The method according to claim 15 wherein after growing at least

one layer of mult-walled fuUerenes, the one flux of cold carbon particles is turned off and the one flux of hot carbon particles is oriented at a pre¬

selected angle off the normal to the surface of the substrate for a pre¬

selected period of time to grow multi-walled nanotubes having a cylindrical

axis inclined at the pre-selected angle to the normal to the surface of the

substrate.

21. The method according to claim 3 wherein the at least one flux of

cold carbon particles is obtained by re-evaporating a portion of the at least

one flux of hot carbon particles towards the substrate surface from at least one temperature controlled substrate oriented at a pre-selected angle with respect to the substrate surface.

22. The method according to claim 3 wherein the at least one flux of

cold carbon particles is obtained by re-evaporating particles of the at least one flux of hot carbon particles from the surface of the substrate back into the interfacial region, and wherein the second pre-selected density and the

second temperature is controlled by controlling the substrate temperature and type of substrate material.

23. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes produced

by the method of claim 12.

24. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a

first longitudinal section substantially perpendicular to the surface and a

second longitudinal section inclined at a pre-selected angle to the first

section produced by the method of claim 13.

25. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled nanotubes on the at least one layer of single-walled fuUerenes inclined at a

pre-selected angle with respect to the normal to the surface produced by the method of claim 14.

26. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled nanotubes on the at least one layer of single-walled fuUerenes having a cylindrical axis substantially perpendicular to the surface and at least one

layer of multi-walled fuUerenes on the at least one layer of single-walled nanotubes produced by the method of claim 15.

27. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a

first longitudinal section substantially perpendicular to the surface and a

second longitudinal section inclined at a pre-selected angle to the first section and at least one layer of multi-walled fuUerenes on the at least one

layer of single-walled nanotubes produced by the method of claim 16.

28. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a

first longitudinal section substantially perpendicular to the surface and a

second longitudinal section inclined at a pre-selected angle to the first

section and at least one layer of multi-walled fuUerenes on the at least one layer of single-walled nanotubes and at least one layer of multi-walled

nanotubes of pre-selected length having a first cylindrical axis which is substantially perpendicular to the surface of the substrate produced by the

method of claim 17.

29. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled or multi-walled

fuUerenes having a first longitudinal section substantially perpendicular to the surface and a second longitudinal section inclined at a pre-selected

angle to the first section and at least one layer of multi-walled fuUerenes on

the at least one layer of single-walled nanotubes and at least one layer of

multi-walled nanotubes of pre-selected length having a first cylindrical axis

which is substantially perpendicular to the surface of the substrate

produced by the method of claim 18.

30. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled nanotubes on the at least one layer of single-walled fuUerenes having a first longitudinal section substantially perpendicular to the surface and a second longitudinal section inclined at a pre-selected angle to the first section and at least one layer of multi-walled fuUerenes on the at least one layer of single-walled nanotubes and at least one layer of multi-walled nanotubes having a first longitudinal section of pre-selected length having a first cylindrical axis which is substantially perpendicular and to the surface of the substrate and a second longitudinal section of pre-selected length having a second cylindrical axis which is inclined at a pre-selected angle to the first cylindrical axis produced by the method of claim 19.

31. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a first longitudinal section substantially perpendicular to the surface and a

layer of single-walled nanotubes and at least one layer of multi-walled

nanotubes of pre-selected length having a cylindrical axis whiGh is inclined

at a pre-selected angle from the normal to the surface produced by the method of claim 20.

32. A product comprising a pre-selected carbon structure selected from the group consisting of one or more layers of planar carbon films, fuUerenes, carbon nanotubes and combinations thereof synthesized by a method including forming a carbon vapor phase interfacial region adjacent to a surface of the substrate by directing at least one carbon particle flux to the surface, and controlling a process of growth of the pre-selected carbon structures by controlling temperature and density of the at least one carbon particle flux and controlling an orientation of the at least one carbon particle flux with respect to the surface of the substrate.

33. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled nanotubes on the at least one layer of single-walled or multi-walled fuUerenes, the single-walled nanotubes having a first cylindrical axis oriented substantially perpendicular and to the surface of the substrate.

34. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled nanotubes on the at least one layer of single-walled fuUerenes, the single-

walled nanotubes having a first longitudinal section with a first cylindrical

axis oriented substantially perpendicular to the surface of the substrate

and the single-walled nanotubes having a second longitudinal section

inclined at a pre-selected angle to the first longitudinal section.

35. A product comprising at least one layer of single-walled fuUerenes

on a surface of a^" substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes inclined at a

pre-selected angle with respect to the normal to the surface.

36. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a

cylindrical axis substantially perpendicular to the surface and at least one layer of multi-walled fuUerenes on the at least one layer of single-walled nanotubes.

37. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a first longitudinal section substantially perpendicular to the surface and a second longitudinal section inclined at a pre-selected angle to the first

section and at least one layer of multi-walled fuUerenes on the at least one layer of single-walled nanotubes.

38. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a

first longitudinal section substantially perpendicular to the surface and a

layer of single-walled nanotubes and at least one layer of multi-walled

nanotubes of pre-selected length having a first cylindrical axis which is

substantially perpendicular and to the surface of the substrate.

39. A product comprising at least one layer of single-walled fuUerenes

on a surface of a substrate and at least one layer of single-walled

layer of single-walled nanotubes and at least one layer of multi-walled nanotubes having a first longitudinal section of pre-selected length having

a first cylindrical axis which is substantially perpendicular and to the surface of the substrate and a second longitudinal section of pre-selected length having a second cylindrical axis which is inclined at a pre-selected angle to the first cylindrical axis.

40. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled

nanotubes on the at least one layer of single-walled fuUerenes having a

first longitudinal section substantially perpendicular to the surface and a

second longitudinal section inclined at a pre-selected angle to the first

section and at least one layer of multi-walled fuUerenes on the at least one

layer of single-walled nanotubes and at least one layer of multi-walled nanotubes of pre-selected length having a cylindrical axis which is inclined at a pre-selected angle from the normal to the surface.

41. A product comprising at least one layer of single-walled fuUerenes on a surface of a substrate and at least one layer of single-walled nanotubes on the at least one layer of single-walled fuUerenes, the single- walled nanotubes having a first longitudinal section with a first cylindrical axis oriented substantially perpendicular to the surface of the substrate and the single-walled nanotubes having a second longitudinal section inclined at a pre-selected angle to the first longitudinal section, the single- walled nanotubes having a p-n semiconductor junction.

42. A product comprising at least one layer of multi-walled fuUerenes on a surface of a substrate and at least one layer of multi-walled nanotubes on the at least one layer of single-walled fuUerenes, the multi-walled nanotubes having a first longitudinal section with a first cylindrical axis

oriented substantially perpendicular to the surface of the substrate and the multi-walled nanotubes having a second longitudinal section inclined at a

pre-selected angle to the first longitudinal section, the multi-walled nanotubes having a p-n semiconductor junction.

43. The method according to claim 11 wherein after growing at least

one layer of multi-walled fuUerenes, the one flux of cold carbon particles is

turned off and the one flux of hot carbon particles is directed at the

substrate for a pre-selected period of time whereby multi-walled nanotubes

of pre-selected length are grown on the multi-walled fuUerenes having a first cylindrical axis oriented substantially perpendicular to the surface of the substrate.

44. The method according to claim 43 wherein after growing the first section of multi-walled nanotubes substantially perpendicular to the surface of the substrate the one flux of hot carbon particles is tilted at a pre-selected angle from the normal axis to the surface of the substrate for a pre-selected period of time to grow a second section of the multi-walled nanotubes wherein the second section has a second cylindrical axis inclined at the pre-selected angle to the first cylindrical axis.